Ventilator with integrated oxygen production

ABSTRACT

A method of providing a breath to a human patient. The patient has a patient connection connected, by a patient circuit, to a ventilator having a first ventilator connection and a different second ventilator connection. Each of the first and second ventilator connections are in fluid communication with the patient circuit. The method includes identifying, with the ventilator, initiation of an inspiratory phase of the breath, delivering a bolus of oxygen to the first ventilator connection before or during the inspiratory phase, and delivering breathing gases comprising air to the second ventilator connection during the inspiratory phase. The ventilator isolates the bolus of oxygen delivered to the first ventilator connection from the breathing gases delivered to the second ventilator connection.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is directed generally to ventilators used toassist human patients with breathing.

2. Description of the Related Art

Respiration may be characterized as including both an inspiratory phaseand an exhalation phase. During the inspiratory phase, inspiratory gasesare drawn into the lungs, and during the exhalation phase, exhalationgases are expelled from the lungs.

Mechanical ventilators are used to assist with breathing. Conventionalventilators typically push inspiratory gases including oxygen into thepatient's lungs. Many patients who use a ventilator also need othertypes of assistance related to treating and maintaining their airwaysand lungs. For example, some patients may use a nebulizer to deliverdrugs to their lungs and/or airways. Further, some patients may needhelp clearing secretions from their lungs and/or airways. Suchassistance is typically provided by a conventional suction device. Thus,in additional to a ventilator, many patients require multiple devicesand traveling with such equipment can be particularly problematic.

Thus, a need exists for ventilators configured to be portable and/orprovide additional functionality beyond delivering inspiratory gasesinto the patient's lungs. The present application provides these andother advantages as will be apparent from the following detaileddescription and accompanying figures.

SUMMARY OF THE INVENTION

An embodiment includes a method of providing a breath to a humanpatient. The human patient has a patient connection connected, by apatient circuit, to a ventilator device. The breath has an inspiratoryphase with a beginning and an end. The method includes delivering abolus of oxygen to the patient circuit at or before the beginning of theinspiratory phase of the breath, terminating the delivery of the bolusof oxygen before the end of the inspiratory phase of the breath, anddelivering breathing gases including air to the patient circuit beforethe end of the inspiratory phase of the breath. The patient circuitdelivers the bolus of oxygen and the breathing gases to the patientconnection. Optionally, the method may further include waiting untilafter the delivery of the bolus of oxygen delivered for the breath hasbeen terminated before delivering the breathing gases.

Optionally, the method may further include receiving a bolus volumevalue. In such embodiments, the bolus of oxygen delivered for the breathhas a volume substantially equal to the bolus volume value.

Optionally, delivering the breathing gases to the patient circuitincludes providing the breathing gases to the patient circuit at a firstinput location of the patient circuit, and delivering the bolus ofoxygen to the patient circuit includes providing the bolus of oxygen tothe patient circuit at a second input location of the patient circuitcloser than the first input location to the patient connection.

Combined the bolus of oxygen and the breathing gases delivered for thebreath have a total inspiratory volume. Optionally, the bolus of oxygendelivered for the breath has a volume that is less than about 75% of thetotal inspiratory volume. Optionally, the bolus of oxygen delivered forthe breath has a volume that is between about 50% of the totalinspiratory volume and about 75% of the total inspiratory volume.

Optionally, the method may further include receiving an oxygen flowequivalent value associated with an oxygen flow rate which if applied tothe patient circuit continuously from the beginning of the inspiratoryphase of the breath to an end of an expiratory phase of the breath wouldproduce a first volume of oxygen. In such embodiments, the bolus ofoxygen delivered for the breath has a second volume that is less thanthe first volume of oxygen.

Optionally, the method may further include detecting the beginning ofthe inspiratory phase of the breath has been initiated by the patient.In such embodiments, the method may further include initiating deliveryof the bolus of oxygen to the patient circuit in response to havingdetected the beginning of the inspiratory phase of the breath has beeninitiated by the patient.

The method may be used with an oxygen source connected to a valve. Insuch embodiments, delivering the bolus of oxygen at or before thebeginning of the inspiratory phase of the breath includes opening thevalve to thereby allow a flow of oxygen from the oxygen source to thepatient circuit. Further, terminating the delivery of the bolus ofoxygen before the end of the inspiratory phase of the breath includesclosing the valve to thereby discontinue the flow of oxygen from theoxygen source to the patient circuit.

The method may be used with an oxygen generator connected to the oxygensource. In such embodiments, the oxygen source is configured to storeoxygen generated by the oxygen generator, the method further includesdetecting a value including at least one of a concentration of theoxygen stored by the oxygen source and a pressure of the oxygen storedby the oxygen source, determining if the detected value is below athreshold value, operating the oxygen generator when the detected valueis determined to be below the threshold value, and delivering oxygengenerated by the oxygen generator to the oxygen source.

The method may be used with a user specified total tidal volume. In suchembodiments, the breathing gases delivered for the breath have a firstvolume, the bolus of oxygen delivered for the breath has a secondvolume, and combined the first and second volumes are substantiallyequal to the user specified total tidal volume.

The method may be used with a user specified peak inspiratory pressurevalue. In such embodiments, a combined pressure of the breathing gasesand the bolus of oxygen delivered for the breath does not exceed theuser specified peak inspiratory pressure value.

The method may be used with a breathing gases delivery conduit and anoxygen delivery conduit. The breathing gases delivery conduit has abreathing gases output located at a first end portion of the patientcircuit away from the patient connection. The oxygen delivery conduithas an oxygen output located at a second end portion of the patientcircuit adjacent to the patient connection. Delivering the breathinggases to the patient circuit may include providing the breathing gasesto the breathing gases output via the breathing gases delivery conduit.Further, delivering the bolus of oxygen to the patient circuit includesproviding the bolus of oxygen to the oxygen output via oxygen deliveryconduit, to thereby isolate the bolus of oxygen delivered for the breathfrom the breathing gases delivered for the breath along at least amajority portion of the patient circuit prior to the patient connection.

Optionally, the patient circuit includes a breathing gases deliveryconduit and an oxygen delivery conduit. In such embodiments, deliveringthe breathing gases to the patient circuit includes providing thebreathing gases to the breathing gases delivery conduit, which deliversthe breathing gases to the patient connection. Further, delivering thebolus of oxygen to the patient circuit includes providing the bolus ofoxygen to the oxygen delivery conduit, which delivers the bolus ofoxygen to the patient connection, thereby isolating the bolus of oxygendelivered for the breath from the breathing gases delivered for thebreath along at least a portion of the patient circuit prior to thepatient connection. Optionally, the bolus of oxygen exits the oxygendelivery conduit and enters the breathing gases delivery conduit at alocation adjacent to the patient connection. Optionally, the bolus ofoxygen exits the oxygen delivery conduit and enters the breathing gasesdelivery conduit at a location within about two centimeters of thepatient connection.

The method may be used with a compressor operable to compress breathinggases. In such embodiments, delivering breathing gases to the patientcircuit includes delivering at least a portion of the breathing gasescompressed by the compressor.

An embodiment includes a ventilator device for use with an oxygen sourceand a patient circuit. The patient circuit is configured to receivebreathing gases and oxygen to provide a breath to a human patient havinga patient connection couplable to the patient circuit. The breath has aninspiratory phase with a beginning and an end. The ventilator deviceincludes a compressor configured to deliver breathing gases to thepatient circuit, and a control system configured to (a) allow the oxygento flow from the oxygen source to the patient circuit at or before abeginning of an inspiratory phase of a breath, (b) prevent the oxygenfrom flowing from the oxygen source to the patient circuit before an endof the inspiratory phase of the breath, and (c) cause the compressor todeliver the breathing gases to the patient circuit before the end of theinspiratory phase of the breath.

Optionally, the ventilator device may include an input configured toreceive a user specified total tidal volume. In such embodiments, thebreathing gases delivered to the patient circuit for the breath have afirst volume, the oxygen allowed to flow to the patient circuit for thebreath has a second volume, and combined the first and second volumesare substantially equal to the user specified total tidal volume.

Optionally, the ventilator device may include an input configured toreceive a user specified peak inspiratory pressure value. In suchembodiments, a combined pressure of the breathing gases delivered to thepatient circuit and the oxygen allowed to flow to the patient circuitfor the breath does not exceed the user specified peak inspiratorypressure value.

Another embodiment includes a ventilator device for use with a patientcircuit. The patient circuit is configured to receive breathing gasesand oxygen to provide a breath to a human patient having a patientconnection couplable to the patient circuit. The breath has aninspiratory phase with a beginning and an end. The ventilator deviceincludes a compressor configured to deliver breathing gases to thepatient circuit, a patient oxygen outlet couplable to the patientcircuit, an oxygen source configured to deliver oxygen to the patientcircuit, and a control system configured to (a) allow the oxygen to flowfrom the oxygen source to the patient circuit at or before a beginningof an inspiratory phase of a breath, (b) prevent the oxygen from flowingfrom the oxygen source to the patient circuit before an end of theinspiratory phase of the breath, and (c) cause the compressor to deliverthe breathing gases to the patient circuit before the end of theinspiratory phase of the breath. Optionally, the ventilator device mayinclude an input configured to receive a user specified total tidalvolume. In such embodiments, the breathing gases delivered to thepatient circuit for the breath have a first volume, the oxygen allowedto flow to the patient circuit for the breath has a second volume, andcombined the first and second volumes are substantially equal to theuser specified total tidal volume. Optionally, the ventilator device mayinclude an input configured to receive a user specified peak inspiratorypressure value. In such embodiments, a combined pressure of thebreathing gases delivered to the patient circuit and the oxygen allowedto flow to the patient circuit for the breath does not exceed the userspecified peak inspiratory pressure value.

An embodiment includes a ventilation system for use with a human patienthaving a patient connection couplable to a patient circuit. The systemincludes a control system, an oxygen source configured to deliver oxygento a patient oxygen outlet couplable to the patient circuit, and acompressor configured to deliver breathing gases to a ventilatorconnection couplable to the patient circuit. The ventilator connectionis different from the patient oxygen outlet. The control system isconfigured to identify an inspiratory phase of a breath, and instructthe oxygen source to deliver the oxygen to the patient oxygen outletbefore or during the inspiratory phase. The oxygen source is configuredto deliver the oxygen to the patient oxygen outlet in response to theinstruction to deliver the oxygen to the patient oxygen outlet. Thecontrol system is further configured to instruct the compressor todeliver the breathing gases to the ventilator connection during theinspiratory phase. The compressor is configured to deliver the breathinggases to the ventilator connection in response to the instruction todeliver the breathing gases to the ventilator connection.

Optionally, the compressor and the ventilator connection may becomponents of a ventilator, and the oxygen source may be external to theventilator.

Optionally, the oxygen source is an internal oxygen source of aventilator. The internal oxygen source has an oxygen inlet in fluidcommunication with the internal oxygen source. In such embodiments, theventilation system may include an external oxygen source in fluidcommunication with the oxygen inlet to deliver oxygen from the externaloxygen source to the internal oxygen source.

Optionally, the ventilation system also includes an oxygen generator influid communication with the oxygen source, the oxygen generatordelivering oxygen to the oxygen source. The compressor, the oxygensource, and the oxygen generator may each be components of a ventilator.Alternatively, the compressor and the oxygen source are each componentsof a ventilator, and the oxygen generator is external to the ventilator.

Optionally, the ventilation system also includes a user interface havingan input configured to receive a user specified total tidal volume. Theuser interface is configured to provide the user specified total tidalvolume to the control system. The control system is configured todetermine a first volume and a second volume. In such embodiments, thebreathing gases delivered for the breath have the first volume, theoxygen delivered for the breath has the second volume, and combined thefirst and second volumes are substantially equal to the user specifiedtotal tidal volume.

Optionally, the ventilation system also includes a user interface havingan input configured to receive a user specified peak inspiratorypressure value. In such embodiments, the user interface is configured toprovide the user specified peak inspiratory pressure value to thecontrol system, and a combined pressure of the breathing gases and theoxygen delivered for the breath does not exceed the user specified peakinspiratory pressure value.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

FIG. 1 is a block diagram illustrating an exemplary system that includesa ventilator for use by a human patient.

FIG. 2A is an illustration of a first embodiment of a passive patientcircuit for use with the ventilator of FIG. 1.

FIG. 2B is a cross-sectional view of a second embodiment of a passivepatient circuit for use with the ventilator of FIG. 1.

FIG. 2C is an enlarged cross-sectional view of a valve assembly of thepassive patient circuit of FIG. 2B illustrated in a closedconfiguration.

FIG. 2D is an enlarged cross-sectional view of the valve assembly of thepassive patient circuit of FIG. 2B illustrated in an open configuration.

FIG. 2E is an exploded view of a valve assembly of the passive patientcircuit of FIG. 2B.

FIG. 3A is a cross-sectional view of an embodiment of an active patientcircuit for use with the ventilator of FIG. 1.

FIG. 3B is an exploded view of a multi-lumen tube assembly of the activepatient circuit of FIG. 3A.

FIG. 3C is an exploded view of an active exhalation valve assembly ofthe active patient circuit of FIG. 3A.

FIG. 3D is an enlarged perspective view of a double bellows member ofthe active exhalation valve assembly of FIG. 3C.

FIG. 3E is an enlarged cross-sectional view of the active patientcircuit of FIG. 3A illustrated with the double bellows member of theactive exhalation valve assembly in a closed position.

FIG. 3F is a first enlarged cross-sectional view of the active patientcircuit of FIG. 3A illustrated with the double bellows member of theactive exhalation valve assembly in an open position.

FIG. 3G is a second enlarged cross-sectional view of the active patientcircuit of FIG. 3A illustrated with the double bellows member of theactive exhalation valve assembly in the open position.

FIG. 4 is block diagram illustrating some exemplary components of theventilator of FIG. 1.

FIG. 5A is a schematic diagram illustrating some exemplary components ofa ventilator assembly of the ventilator of FIG. 1.

FIG. 5B is block diagram illustrating exemplary components of a controlsystem of the ventilator, control signals sent by the control system toexemplary components of the ventilation assembly, and the data signalsreceived by the control system from exemplary components of theventilation assembly.

FIG. 6 is block diagram illustrating some exemplary components of a userinterface of the ventilator of FIG. 1.

FIG. 7A is a schematic diagram illustrating some exemplary components ofan oxygen assembly of the ventilator of FIG. 1.

FIG. 7B is block diagram illustrating exemplary control signals sent bythe control system to exemplary components of the oxygen assembly, andthe data signals received by the control system from exemplarycomponents of the oxygen assembly.

FIG. 8A is a block diagram illustrating an adsorption bed of the oxygenassembly during a first phase of a vacuum pressure swing adsorption(“VPSA”) process.

FIG. 8B is a block diagram illustrating the adsorption bed of the oxygenassembly during a second phase of the VPSA process.

FIG. 8C is a block diagram illustrating the adsorption bed of the oxygenassembly during a third phase of the VPSA process.

FIG. 8D is a block diagram illustrating the adsorption bed of the oxygenassembly during a fourth phase of the VPSA process.

FIG. 9 is an illustration of a metering valve of the oxygen assembly.

FIG. 10A is a perspective view of a first side of a first rotary valveassembly of the oxygen assembly.

FIG. 10B is a perspective view of a second side of the first rotaryvalve assembly.

FIG. 10C is a perspective view of the first side of the first rotaryvalve assembly including a shaft of a motor assembly and omitting otherparts of the motor assembly.

FIG. 10D is a perspective view of the second side of the first rotaryvalve assembly with its outer housing and printed circuit board removed.

FIG. 10E is an exploded perspective view of one of four poppet valves ofthe first rotary valve assembly illustrated with an end cap andfasteners.

FIG. 10F is a cross-sectional view of the first rotary valve assemblywith its second and fourth poppet valves open.

FIG. 10G is a cross-sectional view of the first rotary valve assemblywith its first and third poppet valves open.

FIG. 11 is a graph showing pressure and feed flow experienced by a bedof nitrogen adsorbent material of the oxygen generator during the fourphases of the VPSA process.

FIG. 12 is a flow diagram of a method performed by the control system ofthe ventilator of FIG. 1.

FIG. 13A is an illustration of an optional second rotary valve assemblyof the oxygen assembly depicted with a first one of its four poppetvalves open.

FIG. 13B is an illustration of the optional second rotary valve assemblyof the oxygen assembly depicted with a second one of its four poppetvalves open.

FIG. 13C is an illustration of the optional second rotary valve assemblyof the oxygen assembly depicted with a third one of its four poppetvalves open.

FIG. 13D is an illustration of the optional second rotary valve assemblyof the oxygen assembly depicted with a fourth one of its four poppetvalves open.

FIG. 14A is a graph showing patient airway flow using a prior artventilator during both inspiratory and expiratory phases.

FIG. 14B is a graph showing patient airway pressure using the prior artventilator during both the inspiratory and expiratory phases.

FIG. 15A is a graph showing patient airway flow using the ventilator ofFIG. 1 during both inspiratory and expiratory phases.

FIG. 15B is a graph showing patient airway pressure using the ventilatorof FIG. 1 during both the inspiratory and expiratory phases.

FIG. 16 is a block diagram illustrating an exemplary suction assemblyfor use with the ventilator of FIG. 1.

Like reference numerals have been used in the figures to identify likecomponents.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a block diagram illustrating an exemplary system 10 thatincludes a ventilator 100 for use by a patient 102. The ventilator 100may be configured to provide both traditional volume controlledventilation and pressure controlled ventilation. The ventilator 100 hasan optional multi-lumen tube connection 103, a main ventilatorconnection 104, and an patient oxygen outlet 105. The patient 102 has apatient connection 106 (e.g., a tracheal tube, a nasal mask, amouthpiece, and the like) that is connectable to the main ventilatorconnection 104 and/or the patient oxygen outlet 105 by a patient circuit110.

As will be described below, the patient circuit 110 may be implementedas an active patient circuit or a passive patient circuit. Optionally,when the patient circuit 110 is implemented as an active patientcircuit, the patient circuit 110 may include one or more ports 111configured to be connected to the optional multi-lumen tube connection103. The port(s) 111 allow one or more pressure signals 109 to flowbetween the optional multi-lumen tube connection 103 and the patientcircuit 110. As is apparent to those of ordinary skill in the art, apressure signal may be characterized as gas(es) obtained from a fluid(and/or gas) source for which a pressure is to be measured. The gas(es)obtained are at the same pressure as the fluid (and/or gas) source.

The main ventilator connection 104 is configured to provide gases 112that include room air 114 optionally mixed with oxygen. While identifiedas being “room air,” those of ordinary skill in the art appreciate thatthe room air 114 may include air obtained from any source external tothe ventilator 100. The air 114 is received by the ventilator 100 via apatient air intake 116. The oxygen that is optionally mixed with the air114 may be generated internally by the ventilator 100 and/or receivedfrom an optional low pressure oxygen source 118 (e.g., an oxygenconcentrator), and/or an optional high pressure oxygen source 120. Whenthe oxygen is generated internally, the ventilator 100 may outputexhaust gases (e.g., nitrogen-rich gas 122) via an outlet vent 124.Optionally, the ventilator 100 may include a low pressure oxygen inlet126 configured to be coupled to the optional low pressure oxygen source118 and receive optional low pressure oxygen 128 therefrom. Theventilator 100 may include an optional high pressure oxygen inlet 130configured to be coupled to the optional high pressure oxygen source 120and receive optional high pressure oxygen 132 therefrom.

The patient oxygen outlet 105 is configured to provide doses or pulsesof oxygen 140 to the patient connection 106 (via the patient circuit110) that are synchronized with the patient's breathing. Unlike thegases 112 provided by the main ventilator connection 104, the pulses ofoxygen 140 do not include the air 114.

The gases 112 and/or the pulses of oxygen 140 delivered to the patientcircuit 110 are conducted thereby as inspiratory gases 108 to thepatient connection 106, which at least in part conducts those gases intothe patient's lung(s) 142. Whenever the patient exhales during theexhalation phase, exhaled gases 107 enter the patient circuit 110 viathe patient connection 106. Thus, the patient circuit 110 may containone or more of the following gases: the gases 112 provided by theventilator 100, the pulses of oxygen 140, and the exhaled gases 107. Forease of illustration, the gases inside the patient circuit 110 will bereferred to hereafter as “patient gases.”

Optionally, the ventilator 100 includes a suction connection 150configured to be coupled to an optional suction assembly 152. Theventilator 100 may provide suction 154 to the optional suction assembly152 via the optional suction connection 150. The suction assembly 152may be configured to be connected to the patient connection 106 and/or asuction catheter 812 (see FIG. 16) positionable inside the patientconnection 106.

Referring to FIG. 1, optionally, the ventilator 100 includes a nebulizerconnection 160 configured to be coupled to an optional nebulizerassembly 162. The ventilator 100 may provide gases 164 (e.g., the air114) to the optional nebulizer assembly 162 via the optional nebulizerconnection 160. The optional nebulizer assembly 162 may be configured tobe connected to the patient circuit 110. However, this is not arequirement.

Optionally, the ventilator 100 may include an outlet port 166 throughwhich exhaust 167 may exit from the ventilator 100.

The ventilator 100 may be configured to be portable and powered by aninternal battery (not shown) and/or an external power source (not shown)such as a conventional wall outlet.

Passive Patient Circuits

FIG. 2A is an illustration of a first embodiment of a passive patientcircuit 170 that may be used to implement the patient circuit 110.Referring to FIG. 2A, the passive patient circuit 170 has a first endportion 172 opposite a second end portion 174. The first end portion 172is configured to be connected or coupled (e.g., directly or using ahose, flow line, conduit, or tube) to the main ventilator connection104. The second end portion 174 is configured to be connected or coupledto the patient connection 106 (e.g., directly or using a hose, flowline, conduit, or tube). The passive patient circuit 170 conducts thegases 112 (that include the air 114 optionally mixed with oxygen) fromthe main ventilator connection 104 into the patient connection 106.

In the embodiment illustrated, the passive patient circuit 170 includesan optional bacterial filter 176, a leak valve 177, and a flexible tubesegment 178. The optional bacterial filter 176 may be positioned betweenthe first end portion 172 and the flexible tube segment 178. The gases112 may flow through the optional bacterial filter 176 and on to thepatient connection 106. When present, the bacterial filter 176 helpsprevent bacteria (e.g., received from the patient connection 106) fromentering the ventilator 100 (via the main ventilator connection 104).

The leak valve 177 is coupled to the flexible tube segment 178 near thesecond end portion 174. The leak valve 177 is configured to allow gasesto flow out of the passive patient circuit 170 and into the environmentoutside the passive patient circuit 170. The leak valve 177 may beimplemented as a conventional fixed leak valve configured to allow atmost a threshold amount of pressure inside the passive patient circuit170 during both the inspiratory and exhalation phases.

The leak valve 177 may be implemented as a positive pressure valve thatallows a portion of the patient gases to flow out of the passive patientcircuit 170 and into the environment outside the passive patient circuit170 whenever the pressure inside the passive patient circuit 170 isabove the threshold amount (e.g., environmental pressure). The leakvalve 177 includes a flexible member or flap 179 that covers and sealsan outlet opening 180 when the pressure inside the passive patientcircuit 170 is below the threshold amount. Thus, the leak valve 177 isclosed when the pressure inside the passive patient circuit 170 is belowthe threshold amount.

On the other hand, the flap 179 is configured to be pushed outwardly andaway from the outlet opening 180 when the pressure inside the passivepatient circuit 170 exceeds the threshold amount (e.g., environmentalpressure). Thus, the leak valve 177 is open when the pressure inside thepassive patient circuit 170 is above the threshold amount. Under normaloperating circumstances, the leak valve 177 is open during both theinspiratory and exhalation phases. This means a portion of the patientgases inside the passive patient circuit 170 flow out of the passivepatient circuit 170 through the outlet opening 180 and into theenvironment outside the passive patient circuit 170 during both theinspiratory and exhalation phases.

FIG. 2B is an illustration of a second embodiment of a passive patientcircuit 440 that may be used to implement the patient circuit 110. Thepassive patient circuit 440 includes a connector 442, a flexible tubesegment 444, an open-ended oxygen pulse delivery tube 446, and a valveassembly 448. The flexible tube segment 444 may be implemented using aconventional corrugated or expanding ventilation hose or tubing (e.g.,circuit tubing). The flexible tube segment 444 has a first end portion450 opposite a second end portion 451. The first end portion 450 isconfigured to be connected or coupled to the connector 442. The secondend portion 451 is configured to be connected or coupled to the valveassembly 448.

The connector 442 has a generally tube-shaped connector housing 452 witha first end portion 454 configured to be connected to the mainventilator connection 104 (e.g., directly or using a hose, flow line,conduit, or tube) and to receive the gases 112 (that include the air 114optionally mixed with oxygen) from the main ventilator connection 104.Optionally, the bacterial filter 176 (see FIG. 2A) may be positionedbetween the connector 442 and the main ventilator connection 104. Insuch embodiments, the gases 112 flow through the bacterial filter 176 ontheir way to the connector 442. The bacterial filter 176 helps preventbacteria (e.g., received from the patient connection 106) from enteringthe ventilator 100 (via the main ventilator connection 104).

The connector housing 452 has a second end portion 456 configured to becoupled to the first end portion 450 of the flexible tube segment 444and to provide the gases 112 received by the first end portion 454 tothe flexible tube segment 444. The flexible tube segment 444 conductsthe gases 112 to the valve assembly 448.

The connector 442 includes a hollow tube section 458 that extendsoutwardly from the connector housing 452. In the embodiment illustrated,the tube section 458 is substantially transverse to the connectorhousing 452. However, this is not a requirement. The tube section 458has an open free end portion 459 configured to be connected to thepatient oxygen outlet 105 (e.g., directly or using a hose, flow line,conduit, or tube) and to receive the pulses of oxygen 140 therefrom.Inside the connector housing 452, the tube section 458 is connected tothe oxygen pulse delivery tube 446 and provides the pulses of oxygen 140thereto. In the embodiment illustrated, the tube section 458 isconnected to or includes a branch tube 460 that extends longitudinallyinside the connector housing 452. The branch tube 460 has an open freeend 462 configured to be coupled to the oxygen pulse delivery tube 446and provide the pulses of oxygen 140 thereto. While the tube section 458extends into the connector housing 452, the tube section 458 onlypartially obstructs the flow of the gases 112 through the connectorhousing 452. In other words, the gases 112 pass by or alongside the tubesection 458 and the branch tube 460, if present.

In the embodiment illustrated, the oxygen pulse delivery tube 446extends through the flexible tube segment 444 and at least part way intothe valve assembly 448. Thus, the oxygen pulse delivery tube 446isolates the pulses of oxygen 140 from the gases in the flexible tubesegment 444 along a majority portion of the passive patient circuit 440.The oxygen pulse delivery tube 446 has a first end portion 464configured to be coupled to the branch tube 460. The oxygen pulsedelivery tube 446 has a second end portion 465 that terminates at ornear the patient connection 106. By way of a non-limiting example, thesecond end portion 465 may terminate within about two centimeters of thepatient connection 106. The oxygen pulse delivery tube 446 conducts thepulses of oxygen 140 from the branch tube 460 to the patient connection106. At the same time, the passive patient circuit 440 conducts thegases 112 (that include the air 114 optionally mixed with oxygen) fromthe main ventilator connection 104 into the patient connection 106.

In alternate embodiments, the oxygen pulse delivery tube 446 may beconnected to the patient oxygen outlet 105 (e.g., directly or using ahose, flow line, conduit, or tube) to receive the pulses of oxygen 140from the patient oxygen outlet 105. In such embodiments, the oxygenpulse delivery tube 446 may extend along the outside of the flexibletube segment 444. The second end portion 465 of the oxygen pulsedelivery tube 446 may be connected to a portion of the passive patientcircuit 440 at or near the patient connection 106 to provide the pulsesof oxygen 140 from the branch tube 460 to the patient connection 106.

FIGS. 2C-2E illustrate exemplary components of the valve assembly 448.In the embodiment illustrated, the valve assembly 448 includes a firstvalve housing 468, a second valve housing 469, and a flexiblering-shaped leaf 470.

The first valve housing 468 is configured to be coupled to the patientconnection 106 (see FIG. 2A) and the second valve housing 469 isconfigured to be coupled to the second end portion 451 of the flexibletube segment 444. The first and second valve housings 468 and 469 areconfigured to be coupled together with the ring-shaped leaf 470positioned therebetween. A peripheral portion 473 of the leaf 470 ispositioned within a ring-shaped chamber 474 defined by the first andsecond valve housings 468 and 469. One or more openings 476 are formedin the second valve housing 469 and connect the chamber 474 with theenvironment outside the passive patient circuit 440 (see FIG. 2A).Additionally, one or more openings 478 are formed in the second valvehousing 469 and connect the patient gases inside the passive patientcircuit 440 (see FIG. 2A) with the chamber 474.

Like the flap 179 (see FIG. 2A), the peripheral portion 473 of the leaf470 is configured to transition or deflect from a closed position (seeFIG. 2C) and an open position (see FIG. 2D) when the pressure inside thepassive patient circuit 440 (see FIG. 2A) exceeds the threshold amount(e.g., environmental pressure). When the peripheral portion 473 of theleaf 470 is in the closed position depicted in FIG. 2C, the leaf 470blocks off the one or more openings 478 and isolates the chamber 474from the environment inside the passive patient circuit 440 (see FIG.2A). On the other hand, when the peripheral portion 473 of the leaf 470is in the open position depicted in FIG. 2D, the leaf 470 no longerblocks off the one or more openings 478 and allows the chamber 474 tocommunicate with the patient gases inside and outside the passivepatient circuit 440 (see FIG. 2A). Thus, gases may exit the interior ofthe passive patient circuit 440 (see FIG. 2A) through the opening(s)478, the chamber 474, and the opening(s) 476.

During the inspiratory phase, the ventilator 100 adjusts the pressureinside the passive patient circuit 440 to achieve a preset inspiratorypressure, which places or maintains the leaf 470 in the open position.Some of the patient gases flow to the patient 102 (see FIG. 1), and someof the patient gases flow out through the openings 476.

During the exhalation phase, the ventilator 100 adjusts the pressureinside the passive patient circuit 440 to achieve a baseline or positiveend-expiratory pressure (“PEEP”), which places or maintains the leaf 470in the open position. Some of the exhaled gases 107 (see FIG. 1) fromthe patient 102 flow out through the openings 476, and some of theexhaled gases 107 flow into the passive patient circuit 440 (e.g., intothe flexible tube segment 444).

The breath 102 may pause between the end of the exhalation phase and thebeginning of the inspiratory phase. This pause may be characterized as adead time that occurs between the phases. During a pause, the ventilator100 adjusts the pressure inside the passive patient circuit 440 to PEEP,which places or maintains the leaf 470 in the open position, and causesthe flow of the gases 112 from the ventilator 100 to flow out of thepassive patient circuit 440 through the openings 476. Also, during thistime, at least a portion of the exhaled gases 107 that flowed into thepassive patient circuit 440 during the exhalation phase is “purged” outthrough the openings 476 by the forward moving flow of the gases 112from the ventilator 100.

The combined areas of the openings 476 may be characterized as providinga fixed orifice. Thus, the valve assembly 448 may be characterized asbeing a one-way valve with a fixed orifice. If the combined areas of theopenings 476 is too large, most of the inspiratory flow will leak outthrough the openings 476, leaving little for the patient 102.Conversely, if the combined areas of the openings 476 is too small, theexhaled gases 107 will not be fully purged from the passive patientcircuit 440 during the exhalation phase and the pause between theinspiratory and exhalation phases. By way of a non-limiting example, thevalve assembly 448 may be configured to leak about 20-50 liters perminute (“LPM”) when the pressure inside the passive patient circuit 440is about 10 centimeters of water (“cmH20”).

Active Patient Circuit

FIG. 3A depicts an active patient circuit 600 that may be used toimplement the patient circuit 110 (see FIG. 1). Referring to FIG. 3A,the active patient circuit 600 includes the connector 442, the flexibletube segment 444, the oxygen pulse delivery tube 446, a multi-lumen tubeassembly 602, and an active exhalation valve assembly 604.

Like in the passive patient circuit 440 (see FIG. 2B), the connector 442is coupled to both the first end portion 450 of the flexible tubesegment 444 and the oxygen pulse delivery tube 446. The connector 442receives the gases 112 and provides them to the flexible tube segment444. Further, the connector 442 receives the pulses of oxygen 140 andprovides them to the oxygen pulse delivery tube 446. The pulses ofoxygen 140 exit the oxygen pulse delivery tube 446 at or near thepatient connection 106. By way of a non-limiting example, the pulses ofoxygen 140 may exit the oxygen pulse delivery tube 446 within about 10centimeters of the patient connection 106. In the embodimentillustrated, the pulses of oxygen 140 exit the oxygen pulse deliverytube 446 at or near the active exhalation valve assembly 604.

Optionally, the bacterial filter 176 (see FIG. 2A) may be positionedbetween the connector 442 and the main ventilator connection 104. Insuch embodiments, the gases 112 flow through the bacterial filter 176 ontheir way to the connector 442. When present, the bacterial filter 176helps prevent bacteria (e.g., received from the patient connection 106)from entering the ventilator 100 (via the main ventilator connection104).

The second end portion 451 of the flexible tube segment 444 isconfigured to be coupled to the active exhalation valve assembly 604. Asmentioned above with respect to FIG. 1, the patient circuit 110 mayinclude one or more ports 111 configured to allow the one or morepressure signals 109 to flow between the optional multi-lumen tubeconnection 103 and the patient circuit 110. Referring to FIG. 3C, in theembodiment illustrated, the ports 111 (see FIG. 1) include ports111A-111C spaced apart from one another longitudinally. The ports111A-111C are each formed in the active exhalation valve assembly 604.The port 111C is referred to hereafter as the pilot port 111C.

FIG. 3B is exploded perspective view of the multi-lumen tube assembly602. Referring to FIG. 3B, the multi-lumen tube assembly 602 includes acoupler 608, an elongated tube segment 610, and a connector member 612.The coupler 608 is configured to couple a first end portion 620 of thetube segment 610 to the optional multi-lumen tube connection 103 (seeFIG. 3A). The tube segment 610 has a second end portion 622 opposite thefirst end portion 620. The second end portion 622 is connected to theconnector member 612. Three separate and continuous open-ended channels626A-626C extend longitudinally through the tube segment 610.

The connector member 612 has three connectors 630A-630C configured toconnected to the ports 111A-111C (see FIG. 3C), respectively. Theconnectors 630A and 630B receive pressure signals 109A and 109B (seeFIG. 5A), respectively, from the ports 111A and 111B, respectively. Theconnector 630C conducts a pressure signal 109C (see FIG. 5A) to and fromthe pilot port 111C.

Continuous channels 632A-632C extend from the connectors 630A-630C,respectively, to an end portion 634 of the connector member 612. Whenthe connector member 612 is connected to the tube segment 610, thecontinuous channels 626A-626C of the tube segment 610 are aligned andcommunicate with the continuous channels 632A-632C, respectively. Thus,the multi-lumen tube assembly 602 may be used to conduct the separatepressure signals 109A and 109B, respectively, from the ports 111A and111B, respectively, to the optional multi-lumen tube connection 103.Further, the multi-lumen tube assembly 602 may be used to conduct thepressure signal 109C to the pilot port 111C from the optionalmulti-lumen tube connection 103 and vice versa.

Referring to FIG. 3C, the active exhalation valve assembly 604 includesa first valve housing member 640, a double bellows member 644, and asecond valve housing member 642. The ports 111A and 111B are formed inthe first valve housing member 640 and extend laterally outwardlytherefrom. The pilot port 111C is formed in the second valve housingmember 642 and extends laterally outwardly therefrom.

FIGS. 3E and 3F are enlarged longitudinal cross sectional views thateach show a portion of the active patient circuit 600 that includes theactive exhalation valve assembly 604. The oxygen pulse delivery tube 446has been omitted from FIGS. 3E and 3F. In the embodiment illustrated,the first valve housing member 640 includes an internal obstruction 646positioned between the ports 111A and 111B and configured to partiallyrestrict flow through the first valve housing member 640. Further, asshown in FIGS. 3E and 3F, the interior of the first valve housing member640 includes a first narrowed portion 647A that is adjacent to theobstruction 646 and the port 111A, and a second narrowed portion 647Bthat is adjacent to the obstruction 646 and the port 111B. Thus, thefirst and second narrowed portions 647A and 647B are positioned oppositeone another longitudinally with respect to the obstruction 646 with thefirst narrowed portion 647A being nearer to the patient connection 106(see FIG. 3A) than the second narrowed portion 647B. The ports 111A and111B open into the first and second narrowed portions 647A and 647B,respectively.

Referring to FIG. 3G, together the obstruction 646, the first and secondnarrowed portions 647A and 647B, and the ports 111A and 111B define anairway flow transducer 648 (e.g., a fixed orifice differential pressuretype flow meter) inside the interior of the first valve housing member640. During the inspiration phase, the gases 112 may flow around theobstruction 646 along flow paths identified by curved arrows 649A and649B. During the exhalation phase, the exhaled gases 107 may flow aroundthe obstruction 646 along flow paths opposite those identified by thecurved arrows 649A and 649B.

Referring to FIG. 3C, the first valve housing member 640 has a first endportion 650 configured to be coupled to the patient connection 106 (seeFIG. 3A) and a second end portion 652 configured to be coupled to thesecond valve housing member 642. The second valve housing member 642 hasa first end portion 654 configured to be coupled to the second endportion 652 of the first valve housing member 640, and a second endportion 656 configured to be coupled to the second end portion 451 ofthe flexible tube segment 444. The first end portion 654 of the secondvalve housing member 642 has a generally cylindrical shaped bellowsconnector portion 657. An opening 658 of the pilot port 111C is formedin the bellows connector portion 657 of the second valve housing member642.

Referring to FIG. 3D, the double bellows member 644 has a generallyring-like outer shape with a centrally located through-channel 660. Thedouble bellows member 644 has a hollow interior 662 with a ring-shapedopen end 664 opposite a ring-shaped closed end 666 (see FIG. 3C). In theembodiment illustrated, the double bellows member 644 has concertinaedinner and outer sidewalls 668 and 669. The inner sidewall 668 extendsbetween the open end 664 and the closed end 666 along the centrallylocated through-channel 660. The outer sidewall 669 extends between theopen end 664 and the closed end 666 and is spaced radially outwardlyfrom the inner sidewall 668. The hollow interior 662 is defined betweenthe inner and outer sidewalls 668 and 669. Each of the inner and outersidewalls 668 and 669 have bellows portions 668A and 669A (see FIG. 3C),respectively, which each have an undulating longitudinal cross-sectionalshape. In alternate embodiments, the inner and outer sidewalls 668 and669 may include different numbers of convolutions that define a singleconvolute or more than two convolutes.

The open end 664 is configured to fit over the bellows connector portion657 of the second valve housing member 642 like a sleeve. When thebellows connector portion 657 of the second valve housing member 642 isreceived inside the open end 664 of the double bellows member 644, thebellows portions 668A and 669A (see FIG. 3C) of the inner and outersidewalls 668 and 669, respectively, are positioned adjacent to thebellows connector portion 657 of the second valve housing member 642.Thus, the opening 658 of the pilot port 111C is in communication with aportion of the hollow interior 662 positioned between the bellowsportions 668A and 669A (see FIG. 3C) of the inner and outer sidewalls668 and 669, respectively.

Referring to FIG. 3C, when the bellows connector portion 657 of thesecond valve housing member 642 is received inside the open end 664 ofthe double bellows member 644, the opening 658 of the pilot port 111Cmay provide the pressure signal 109C to the interior of the doublebellows member 644.

Referring to FIGS. 3E and 3F, as mentioned above, the second end portion652 of the first valve housing member 640 is configured to be coupled tothe first end portion 654 of the second valve housing member 642. Whenso coupled together, a ring-shaped chamber 670 is defined between thesecond end portion 652 of the first valve housing member 640 and thefirst end portion 654 of the second valve housing member 642. One ormore openings 672 (see FIG. 3C) are formed in the first valve housingmember 640 and connect the chamber 670 with the environment outside theactive patient circuit 600 (see FIG. 3A). The bellows portion 668A and669A (see FIG. 3C) of the outer sidewall 669 and a peripheral portion674 of the closed end 666 is positioned within the chamber 670.

The double bellows member 644 is constructed from a flexible material(e.g., silicone rubber and the like). The bellows portions 668A and 669A(see FIG. 3C) of the inner and outer sidewalls 668 and 669,respectively, are configured to compress to transition the closed end666 from a closed position (see FIG. 3E) to an open position (see FIG.3F). When the bellows portions 668A and 669A (see FIG. 3C) are notcompressed, the closed end 666 is in the closed position depicted inFIG. 3E. In this configuration, the closed end 666 of the double bellowsmember 644 abuts a ring-shaped seat 680 formed in the first valvehousing member 640 and defining a portion of the chamber 670. This sealsthe chamber 670 from the interior of the active patient circuit 600. Onthe other hand, when the bellows portions 668A and 669A (see FIG. 3C)are compressed toward the second valve housing member 642, the closedend 666 is in the open position depicted in FIG. 3F. In thisconfiguration, the closed end 666 is spaced away from the seat 680. Thisopens the chamber 670 by connecting the chamber 670 with the inside ofthe active patient circuit 600. Thus, when the closed end 666 of thedouble bellows member 644 is in the open position, patient gases insidethe active patient circuit 600 may exit therefrom through the chamber670 and the opening(s) 672 (see FIG. 3C).

The closed end 666 of the double bellows member 644 is selectively movedbetween the open and closed positions by controlling the pressure insidethe double bellows member 644 using the pilot port 111C. For example,the closed end 666 of the double bellows member 644 may be placed in theclosed position (see FIG. 3E) during the inspiratory phase, and in theopen position during the expiratory phase. In such embodiments, at thestart of the inspiratory phase, the pilot port 111C provides a flow ofgases (as the pressure signal 109C) having the same pressure as thegases 112 (provided to the active patient circuit 600) to the hollowinterior 662 of the double bellows member 644. An area of the doublebellows member 644 exposed to a pressure provided by the patient 102(see FIG. 1) via the patient connection 106 is less than an area exposedto the pressure of the pressure signal 109C, so that even if the twopressures are equal, the closed end 666 of the double bellows member 644will move to or remain in the closed position against the seat 680. Atthe end of the inspiratory phase, the pilot port 111C provides a flow ofgases (as the pressure signal 109C) having a pilot pressure to thehollow interior 662 of the double bellows member 644. The pilot pressureis less than the pressure provided by the patient 102 (see FIG. 1) viathe patient connection 106 and causes the closed end 666 of the doublebellows member 644 to move to or remain in the open position (see FIG.3F) spaced apart from the seat 680. Thus, the pressure inside the hollowinterior 662 of the double bellows member 644 may be alternated betweena closed pressure that is the same pressure as the gases 112 (providedto the active patient circuit 600), and an open pressure that is equalto the pilot pressure. If desired, the pressure inside the hollowinterior 662 of the double bellows member 644 may be adjusted byallowing the flow of gases (in the pressure signal 109C) to flow fromthe hollow interior 662 to the pilot port 111C.

Ventilator

FIG. 4 is a block diagram illustrating some exemplary components of theventilator 100. Referring to FIG. 4, in addition to the componentsdiscussed with respect to FIG. 1, the ventilator 100 includes aventilation assembly 190, a user interface 200, an oxygen assembly 210,a control system 220, and conventional monitoring and alarm systems 221.Because those of ordinary skill in the art are familiar withconventional monitoring and alarm systems 221, they will not bedescribed in detail herein.

The control system 220 receives input information 196 (e.g., settings,parameter values, and the like) from the user interface 200, andprovides output information 198 (e.g., performance information, statusinformation, and the like) to the user interface 200. The user interface200 is configured to receive input from a user (e.g., a caregiver, aclinician, and the like associated with the patient 102 depicted inFIG. 1) and provide that input to the control system 220 in the inputinformation 196. The user interface 200 is also configured to displaythe output information 198 to the user.

As mentioned above, referring to FIG. 1, the patient circuit 110 mayinclude the optional port(s) 111 configured to allow one or morepressure signals 109 to flow between the optional multi-lumen tubeconnection 103 and the patient circuit 110. Referring to FIG. 3, theoptional multi-lumen tube connection 103 is configured to provide thepressure signal(s) 109 to the ventilation assembly 190.

As will be explained below, the ventilation assembly 190 may receive oneor more control signals 192 from the control system 220, and theventilation assembly 190 may provide one or more data signals 194 to thecontrol system 220. Similarly, the oxygen assembly 210 may receive oneor more control signals 260 from the control system 220, and the oxygenassembly 210 may provide one or more data signals 262 to the controlsystem 220. The control signals 192 and 260 and the data signals 194 and262 may be used by the control system 220 to monitor and/or controlinternal operations of the ventilator 100.

Ventilation Assembly

FIG. 5A is a schematic diagram illustrating some exemplary components ofthe ventilation assembly 190. FIG. 5B is a block diagram illustratingexemplary components of the control system 220, the control signal(s)192 sent by the control system 220 to exemplary components of theventilation assembly 190, and the data signals 194 received by thecontrol system 220 from exemplary components of the ventilation assembly190.

Referring to FIG. 5A, the ventilation assembly 190 includes anaccumulator 202, an internal flow transducer 212, a blower 222, anairway pressure transducer 224, an airway flow transducer module 225, anexhalation control assembly 226, an oxygen sensor 227, an ambientpressure transducer 228, an inlet silencer 229, and an internal bacteriafilter 230. At the beginning of the inspiratory phase, the air 114 maybe drawn into the ventilator 100 (see FIGS. 1 and 4) through the patientair intake 116, which may be configured to filter dust and/or othertypes of particles from the air. At least a portion of the air 114 flowsinto the accumulator 202 where the air 114 may optionally be mixed withoxygen 250 received from the oxygen assembly 210, the low pressureoxygen 128 (received from the low-pressure external oxygen source 118depicted in FIG. 1), combinations and/or sub-combinations thereof, andthe like. As illustrated in FIG. 4, the high pressure oxygen 132(received from the high-pressure external oxygen source 120 depicted inFIG. 1) flows into the oxygen assembly 210 and may be delivered to theaccumulator 202 (see FIG. 5A) as the oxygen 250.

Referring to FIG. 5A, the accumulator 202 may also serve as a mufflerfor the patient air intake 116.

The inlet silencer 229 helps muffle sounds created by the oxygenassembly 210 (e.g., by a compressor 302 illustrated in FIG. 7A).

The oxygen sensor 227 is connected to the accumulator 202 and measuresan oxygen concentration value of the gas(es) inside the accumulator 202.This value approximates the oxygen concentration value of a gas 252 thatexits the accumulator 202. Referring to FIG. 5B, the oxygen sensor 227provides an oxygen concentration signal 276 encoding the oxygenconcentration value to the control system 220. The control system 220processes the oxygen concentration signal 276 to obtain a measure of howmuch oxygen is in the gas 252 (e.g., expressed as a percentage).Referring to FIG. 4, the output information 198 sent by the controlsystem 220 to the user interface 200 may include the measure of how muchoxygen is in the gas 252. The user interface 200 may display thismeasure to the user (e.g., the patient 102 depicted in FIG. 1).

Referring to FIG. 5A, optionally, the accumulator 202 includes or isconnected to the low-pressure oxygen inlet 126. When the low-pressureoxygen 128 is supplied by the low-pressure external oxygen source 118(see FIG. 1), the control system 220 may not control the resultingoxygen concentration flowing to the patient 102. In other words, thelow-pressure oxygen 128 may simply flow into the accumulator 202, bemixed with the air 114, and pushed into the patient circuit 110 (seeFIG. 1) by the blower 222. When this occurs, the ventilator 100 does notcontrol the oxygen concentration delivered to the patient 102 in theinspiratory gases 108 (see FIG. 1), but does control the delivery of theinspiratory gases 108 during the inspiratory phase of each breath.

The gas 252 exiting the accumulator 202 includes the air 114 andoptionally one or more of the oxygen 250 and the oxygen 128. The gas 252may be conducted via a conduit or flow line 214 to the internal flowtransducer 212. For ease of illustration, a portion of the flow line 214between the accumulator 202 and the internal flow transducer 212 hasbeen omitted from FIG. 5A. The gas 252 flows through the internal flowtransducer 212, which measures a flow rate of the gas 252 and provides aflow signal 270 (see FIG. 5B) encoding the flow rate to the controlsystem 220 (see FIG. 5B). The flow signal 270 may be implemented as ananalog electric signal. Referring to FIG. 5B, the control system 220uses the flow signal 270 to control the blower 222. By way of anon-limiting example and as shown in FIG. 5A, the internal flowtransducer 212 may be implemented using a flow transducer having a fixedorifice differential pressure configuration.

The internal flow transducer 212 may be used to detect when the patient102 (see FIG. 1) has initiated a breath. In particular, the internalflow transducer 212 may be used in this manner when the patient circuit110 (see FIG. 1) is implemented as a passive patient circuit (e.g., thepassive patient circuit 170, the passive patient circuit 440, and thelike). The flow of gases through the flow line 214 is not determinedentirely by the blower 222. Instead, the patient's breathing efforts maycause a change in the flow rate through the flow line 214. Thus, thecontrol system 220 may identify that the patient 102 has initiated abreath by identifying a change in the flow rate (encoded in the flowsignal 270) through the flow line 214.

The internal flow transducer 212 may include or be connected to an autozero solenoid valve SV5 configured to be selectively activated anddeactivated by a control signal 285 (see FIG. 5B) sent by the controlsystem 220. The internal flow transducer 212 may drift over time,causing flow rate measuring errors. To compensate for this error,occasionally (e.g., periodically) the control system 220 energizes (oractivates) the auto zero solenoid valve SV5 (using the control signal285) and determines an offset value for the internal flow transducer212. After determining the offset value, the control system 220 uses theoffset value to compensate future readings (based on the flow signal270) accordingly.

Referring to FIG. 5A, after the internal flow transducer 212, the gas252 flows into the blower 222. The gas 252 may be conducted into theblower 222 via the flow line 214. For ease of illustration a portion ofthe flow line 214 between the internal flow transducer 212 and theblower 222 has been omitted from FIG. 5A. Referring to FIG. 5B, theblower 222 may be implemented as a radial blower driven by a motor 272.By way of a non-limiting example, the motor 272 may be implemented as abrushless direct current motor. By way of additional non-limitingexamples, the blower 222 may be implemented as a compressor, a pump, andthe like. The motor 272 has an operating speed that is controlled by thecontrol system 220. By way of a non-limiting example, the control system220 may continuously control the operating speed of the motor 272.

Referring to FIG. 5A, the gas 252 flows out of the blower 222 and into aconduit or flow line 273. The flow line 273 may include one or moreports (e.g., a blower port 275A and a port 275B) configured to provideaccess to the flow of the gas 252 in the flow line 273. The flow line273 conducts the flow of the gas 252 from the blower 222 to the internalbacteria filter 230. For ease of illustration a portion of the flow line273 between the ports 275A and 275B has been omitted from FIG. 5A.

Referring to FIG. 5A, the airway pressure transducer 224 measures airwaypressure of the gas 252 flowing out of the blower 222 and toward themain ventilator connection 104. Referring to FIG. 5B, the airwaypressure transducer 224 provides an electrical pressure signal 274encoding these pressure values to the control system 220. The electricalpressure signal 274 is used to control patient pressure during theinspiratory and exhalation phases. The electrical pressure signal 274 isalso used by the monitoring and alarm systems 221 (see FIG. 4).Optionally, the ventilator 100 (see FIGS. 1 and 4) may include one ormore redundant airway pressure transducers (not shown) like the airwaypressure transducer 224 to provide a failsafe backup for the airwaypressure transducer 224.

The airway pressure transducer 224 may be used by the control system 220to detect a pressure change and in response to detecting a pressurechange, instruct the blower 222 to increase or decrease its speed toadjust the pressure inside the flow line 273. Thus, the control system220 may use the electrical pressure signal 274 to deliver pressureventilation and/or help ensure the pressure inside the flow line 273does not exceed an user supplied peak inspiratory pressure value (e.g.,entered via the pressure control input 237 depicted in FIG. 6).

Referring to FIG. 5A, the airway flow transducer module 225 includes adifferential pressure transducer PT4, auto zero solenoid valves SV1 andSV2, and purge solenoid valves SV3 and SV4. Referring to FIG. 5B, thecontrol system 220 may selectively activate or deactivate the solenoidvalves SV1-SV4 using control signals 281-284, respectively.

Referring to FIG. 1, as mentioned above, the patient circuit 110 mayinclude the one or more optional ports 111. FIG. 5A illustrates animplementation of the ventilation assembly 190 configured for use withthe patient circuit 110 implemented as an active patient circuit (e.g.,the active patient circuit 600 depicted in FIG. 3A, and the like). Inalternate embodiments configured for use with the patient circuit 110implemented as a passive patient circuit (e.g., the passive patientcircuit 170 depicted in FIG. 2A, the passive patient circuit 440depicted in FIG. 2B, and the like), the ports 275A and 275B, the airwayflow transducer module 225, and the exhalation control assembly 226 maybe omitted from the ventilation assembly 190.

The airway flow transducer module 225, and the exhalation controlassembly 226 illustrated in FIG. 5A are configured for use with anactive patient circuit (e.g., the active patient circuit 600 depicted inFIG. 3A) that includes the airway flow transducer 648 (see FIG. 3G).Referring to FIG. 5A, the first and second ports 111A and 111B (see FIG.3C) send first and second pressure signals 109A and 109B, respectively,(e.g., via separate lines or channels) to the differential pressuretransducer PT4. The differential pressure transducer PT4 has input portsPA and PB configured to receive the first and second pressure signals109A and 109B, respectively. The differential pressure transducer PT4determines a differential pressure based on the first and secondpressure signals 109A and 109B, converts the differential pressure to asignal 277 (see FIG. 5B), and (as illustrated in FIG. 5B) transmits thesignal 277 to the control system 220 for further processing thereby. Byway of a non-limiting example, the signal 277 may be an analog signal.

The signal 277 may be used to detect when the patient 102 (see FIG. 1)has initiated a breath. The flow of gases through the active patientcircuit 600 (see FIG. 3A) is not determined entirely by the blower 222.Instead, the patient's breathing efforts may cause a change in the flowrate through the active patient circuit 600. Thus, the control system220 may identify that the patient 102 has initiated a breath byidentifying a change in the flow rate (encoded in the signal 277)through the active patient circuit 600.

The auto zero solenoid valves SV1 and SV2 are connected to the inputports PA and PB, respectively, of the differential pressure transducerPT4. Further, each of the auto zero solenoid valves SV1 and SV2 isconnected to ambient pressure. The differential pressure transducer PT4can drift over time causing flow measuring errors. To compensate forthis error, occasionally (e.g., periodically) the control system 220energizes (or activates) the auto zero solenoid valves SV1 and SV2(using the control signals 281 and 282, respectively) and determines anoffset value for the differential pressure transducer PT4. Then, thecontrol system 220 deactivates the auto zero solenoid valves SV1 and SV2(using the control signals 281 and 282, respectively). After determiningthe offset value, the control system 220 uses the offset value tocompensate future readings (based on the signal 277) accordingly.

The purge solenoid valves SV3 and SV4 are connected to the blower port275A. Referring to FIG. 5B, the control system 220 occasionally (e.g.,periodically) energizes (or activates) the purge solenoid valves SV3 andSV4 (using the control signals 283 and 284, respectively), which allowsdry gas from the line 273 (see FIG. 5A) to flow through the lines,ports, and/or channels (e.g., the optional multi-lumen tube connection103, the channels 626A and 626B, the channels 632A and 632B, the ports111A and 111B, and the like) conducting the pressure signals 109A and109B to purge those structures of any moisture that may have condensedfrom the humid patient breathing gas.

The exhalation control assembly 226 includes an accumulator A2, apressure transducer PT8, and solenoid valves SV6-SV8. The accumulator A2has three ports 267-269 and an internal pressure (referred as the “pilotpressure”). The pressure transducer PT8 is connected to the accumulatorA2, measures the internal pressure inside the accumulator A2, andtransmits this value to the control system 220 in an electrical pressuresignal 271 (see FIG. 5B).

Referring to FIG. 5B, the solenoid valves SV6-SV8 are configured to beselectively activated and deactivated by control signals 286-288,respectively, sent by the control system 220 to the solenoid valvesSV6-SV8, respectively. Turning to FIG. 5A, the solenoid valve SV6 isconnected to the first port 267 of the accumulator A2, the port 275B,and the pilot port 111C (see FIG. 3C) of the active patient circuit 600(see FIG. 3A). The solenoid valve SV7 is connected to the second port268 of the accumulator A2 and the port 275B. The solenoid valve SV8 isconnected between the third port 269 of the accumulator A2 and theoutlet port 166.

The exhalation control assembly 226 provides the pilot pressure (fromthe accumulator A2) to the pilot port 111C (see FIG. 3C) of the activepatient circuit 600 (see FIG. 3A), which as described above, controlsthe active exhalation valve assembly 604. At the start of theinspiratory phase, the control system 220 activates the solenoid valveSV6 (using the control signal 286), which connects the pressure of thegases 252 (via the port 275B) to the pilot port 111C. This closes theactive exhalation valve assembly 604. At the end of the inspiratoryphase, the control system 220 deactivates the solenoid valve SV6 (usingthe control signal 286), which connects the internal pressure of theaccumulator A2 (or the pilot pressure) to the active exhalation valveassembly 604, which opens the active exhalation valve assembly 604.

The control system 220 uses the solenoid valves SV7 and SV8 to controlthe pilot pressure inside the accumulator A2 using feedback provided bythe pressure transducer PT8 (via the electrical pressure signal 271depicted in FIG. 5B) to set a pilot pressure for the exhalation phasethat will achieve the desired PEEP. For example, the control system 220may lower the pilot pressure inside the accumulator A2 by activating thesolenoid valve SV8 (using the control signal 288) to vent some of thegases inside the accumulator A2 via the outlet port 166 as the exhaust167. Conversely, the control system 220 may increase the pilot pressureby activating the solenoid valve SV7 (using the control signal 287) toadd some of the gases 252 (obtained via the port 275B) to the inside ofthe accumulator A2.

Referring to FIG. 5B, the control system 220 uses the electricalpressure signal 274 (received from the airway pressure transducer 224)to help control the blower 222. The control system 220 sends a controlsignal 278 to the motor 272, which directs the blower 222 to provide adesired flow rate and/or a desired amount of pressure to the patient102. As mentioned above, the flow signal 270 is used to help control theflow rate of the gas 252 during the inspiratory and exhalation phases.Similarly, the electrical pressure signal 274 is used to control thepatient pressure during the inspiratory and exhalation phases.

As explained above, the ventilator 100 adjusts the pressure inside thepatient circuit 110 (e.g., the passive patient circuit 440 illustratedin FIG. 2B) to achieve the preset inspiratory pressure during theinspiratory phase, the baseline pressure or PEEP during the exhalationphase, and PEEP during the pause between the inspiratory and exhalationphases. These adjustments are made by the control system 220, whichmonitors the electrical pressure signal 274, and uses the control signal278 to increase or decrease the speed of the motor 272 to achieve thedesired pressure inside the patient circuit 110.

The ambient pressure transducer 228 measures an atmospheric pressurevalue. The ambient pressure transducer 228 provides an ambientelectrical pressure signal 280 encoding the atmospheric pressure valueto the control system 220. The control system 220 uses the ambientelectrical pressure signal 280 to correct the flow rate values (receivedvia the flow signal 270), and/or the exhaled tidal volume value(calculated by the control system 220) to desired standard conditions.

Referring to FIG. 5A, as mentioned above, the flow line 273 conducts theflow of the gas 252 from the blower 222 to the internal bacteria filter230. After the gas 252 passes through the internal bacteria filter 230,they exit the internal bacteria filter 230 as the gases 112 and enterthe patient circuit 110 (see FIG. 1) via the main ventilator connection104. The internal bacteria filter 230 helps prevent bacteria in thepatient circuit 110 from contaminating the ventilator 100.

User Interface

FIG. 6 is a block diagram illustrating some exemplary components of theuser interface 200. As mentioned above, FIG. 4 illustrates the outputinformation 198 sent by the control system 220 to exemplary componentsof the user interface 200, and the input information 196 received by thecontrol system 220 from exemplary components of the user interface 200.

Referring to FIG. 6, the user interface 200 is configured to receiveoperating parameter values from a user (e.g., a clinician) and todisplay information to the user. For example, the user interface 200 mayinclude a display device 240 (e.g., a liquid crystal display), a modeinput 235, an inspiratory time input 236, a pressure control input 237,a pressure support input 238, an activate oxygen generator input 239 foractivating oxygen generation (described below), a tidal volume input242, an oxygen flow equivalent 244, a fraction of inspired oxygen(“FI02”) input 246, a breath rate input 247, an oxygen pulse volumeinput 251, an activate suction input 248 for activing the suctionassembly 152 (see FIG. 1), and an activate nebulizer input 249 foractiving the nebulizer assembly 162 (see FIG. 1).

The beginning of the inspiratory phase is referred to as “initiation.”The mode input 235 is configured to receive an indication as to whetherthe ventilator 100 determines when each breath is initiated or thepatient 102 determines when each breath is initiated. The breath rateinput 247 is configured to receive a rate (e.g., breaths per minute) atwhich breaths are to be delivered. If the user has indicated (using themode input 235) that the ventilator 100 determines when each breath isinitiated, the ventilator 100 will deliver breaths in accordance withthe rate received by the breath rate input 247 (e.g., at regularly timedintervals). On the other hand, If the user has indicated (using the modeinput 235) that the patient 102 initiates each breath, the ventilator100 will automatically deliver breaths as needed to ensure the patient102 receives breaths at least as frequently as indicated by the ratereceived by the breath rate input 247.

The ventilator 100 may identify the end of the inspiratory phase usingtime or a rate of flow of the gases 112 to the patient 102. In thelatter case, the patient 102 determines when the inspiratory phase ends.The inspiratory time input 236 is configured to receive a valueindicating a duration T_(i) from the initiation of each breath to theend of the inspiratory phase. The ventilator 100 may use the value(indicating the duration T_(i)) to identify the end of the inspiratoryphase. The pressure support input 238 receives an indication that theuser would like to use the rate of flow of the gases 112 to the patient102 (instead of the value indicating the duration T_(i)) to end theinspiratory phase. For example, the ventilator 100 may end theinspiratory phase of a breath when the flow rate of the gases 112 isonly about 25% of a peak flow rate that occurred during the breath.

The ventilator 100 is configured to deliver the gases 112 alone, or acombination of the gases 112 and the pulses of oxygen 140. As mentionedabove, the ventilator 100 may be configured to provide both traditionalvolume controlled ventilation and pressure controlled ventilation. Touse pressure control, the user may use the pressure control input 237 toenter a peak inspiratory pressure value. The ventilator 100 uses thepeak inspiratory pressure value to configure the gases 112 alone, or thecombination of the gases 112 and the pulses of oxygen 140 such that thepressure during the inspiratory phases is at most the peak inspiratorypressure value.

The FI02 input 246 is configured to receive an oxygen concentrationvalue. The ventilator 100 uses the oxygen concentration value toconfigure the gases 112 to have an oxygen concentration equal to orapproximating the oxygen concentration value.

The oxygen pulse volume input 251 is configured to receive an oxygenpulse volume value (e.g., expressed in milliliters, or a value within apredefined range, such as from 1 to 10, and the like). The ventilator100 uses the oxygen pulse volume value to configure each of the pulsesof oxygen 140 to have a volume equal to or approximating the oxygenpulse volume value.

The tidal volume input 242 is configured to receive a desired totaltidal volume value. Referring to FIG. 15A, the ventilator 100 uses thedesired total tidal volume value to output a volume of the gases 112(illustrated by area 586 and described below) and one of the pulses ofoxygen 140 (illustrated by area 584 and described below) during eachbreath. For each breath delivered, the total tidal volume delivered isthe combined volumes of gases 112 and the pulse of oxygen 140 deliveredduring the breath.

The oxygen flow equivalent 244 is configured to receive a desired oxygendelivery rate (expressed in liters per minute) that identifies a rate atwhich a hypothetical continuous oxygen flow may be bled into aconventional ventilator or the patient circuit 110 (see FIG. 1) from anexternal source (e.g., a stand-alone oxygen concentrator). Theventilator 100 uses this value to configure each of the pulses of oxygen140 (see FIG. 1) to deliver an amount of oxygen that would provideequivalent oxygenation to the patient 102 (see FIG. 1) as thehypothetical continuous oxygen flow.

Oxygen Assembly

FIG. 7A is a schematic diagram illustrating some exemplary components ofthe oxygen assembly 210. FIG. 7B illustrates the control signals 260sent by the control system 220 to exemplary components of the oxygenassembly 210, and the data signals 262 received by the control system220 from exemplary components of the oxygen assembly 210.

Referring to FIG. 7A, the oxygen assembly 210 is configured to receivethe high-pressure oxygen 132 and/or generate oxygen 346 (see FIG. 8B)and provide the oxygen 250 to the accumulator 202 (see FIG. 5A) of theventilation assembly 190 and/or provide the pulses of oxygen 140 to thepatient oxygen outlet 105. The oxygen assembly 210 may be configured toprovide up to about two liters per minute (“LPM”) of approximately 90%pure oxygen. In the embodiment illustrated, the oxygen assembly 210includes an adsorption bed 300, the compressor 302, a first rotary valveassembly 306, two pressure transducers PT2 and PT3, two pressureregulators R1 and R2, an outlet silencer 311, optional solenoid valvesSV9 and SV10, an oxygen tank 312, an oxygen sensor 314, a metering valve320, and an optional second rotary valve assembly 330. Together thecompressor 302, the first rotary valve assembly 306, the adsorption bed300, and the pressure regulators R1 and R2 may be characterized as beingan oxygen generator or oxygen concentrator. The oxygen generatorillustrated in the figures and described below implements a vacuumpressure swing absorption (“VPSA”) process. In alternate embodiments,the ventilator 100 may include an oxygen generator that implements atleast one of a polymer membrane separation process, an ion transportseparation process, a cryogenic process, and the like. Further, the VPSAprocess described below is a subset of Pressure Swing Adsorption (PSA)and the oxygen generator may be configured to implement a PSA processother than the VPSA process described below.

The adsorption bed 300 is configured to harvest oxygen from the air 114received via the patient air intake 116. As will be explained below, theadsorption bed 300 may be configured to at least partially implement aVPSA process that includes a cycle with four phases (described below).The cycle alternately generates the oxygen 346 (see FIG. 8B) and thenitrogen-rich gas 122. As the ventilator 100 operates, the cycle isrepeated until enough oxygen has been generated to fill the oxygen tank312. When the oxygen tank 312 is full, the cycles are halted or sloweduntil a sufficient amount of the oxygen in the oxygen tank 312 has beenremoved. Then, the cycles are resumed again or sped up as appropriate.The nitrogen-rich gas 122 generated by each cycle is exhausted to theoutside environment via the outlet vent 124.

FIGS. 8A-8D are block diagrams illustrating some exemplary components ofthe adsorption bed 300. Referring to FIGS. 8A-8D, in the embodimentillustrated, the adsorption bed 300 includes at least one housing 340having a first end 341 opposite a second end 343. The housing 340contains a bed of nitrogen adsorbent material 344 (such as zeolite)between its first and second ends 341 and 343. The bed of nitrogenadsorbent material 344 preferentially absorbs nitrogen. For ease ofillustration, the adsorption bed 300 will be described as including asingle housing containing a single bed of nitrogen adsorbent material.In alternate embodiments, the adsorption bed 300 may include two or morebeds like the bed of nitrogen adsorbent material 344 that are eachhoused inside separate housings like the housing 340.

As mentioned above, the VPSA process includes a cycle with four phases.FIG. 8A illustrates the adsorption bed 300 during a first phase.Referring to FIG. 8A, during the first phase, the air 114 is pumped intothe housing 340 by the compressor 302 (see FIG. 7A). When the housing340 is pressurized with the air 114 (by the compressor 302), nitrogen inthe air is preferentially adsorbed by the bed of nitrogen adsorbentmaterial 344, which leaves behind unadsorbed oxygen. The bed of nitrogenadsorbent material 344 may include interstitial spaces in which theunadsorbed oxygen is held or trapped.

FIG. 8B illustrates the adsorption bed 300 during a second phase of acycle of the VPSA process. During the second phase, the oxygen 346 ispumped from the housing 340. The oxygen 346 flows from the interstitialspaces and into the oxygen tank 312 (see FIG. 7A).

FIG. 8C illustrates the adsorption bed 300 during a third phase of acycle of the VPSA process. During the third phase, the nitrogen-rich gas122 is pulled from the bed of nitrogen adsorbent material 344 in thehousing 340 (by the compressor 302 illustrated in FIG. 7A) and vented tothe outside environment via the outlet vent 124 (see FIG. 7A).

FIG. 8D illustrates the adsorption bed 300 during a fourth phase of acycle of the VPSA process. During the fourth phase, a flow of “purge”oxygen 348 (e.g., from the oxygen tank 312 illustrated in FIG. 7A) maybe used to help draw out the nitrogen-rich gas 122 and regenerate thebed of nitrogen adsorbent material 344.

Returning to FIG. 7A, the oxygen 346 (see FIG. 8B) removed from theadsorption bed 300 flows through the pressure regulator R2, and into theoxygen tank 312 where the oxygen 346 is stored. While this is occurring,the metering valve 320 may be closed, and the pressure regulator R1 maybe closed to prevent flow back into the adsorption bed 300.Alternatively, the metering valve 320 may be at least partially open toallow some of the oxygen 346 to flow to the optional second rotary valveassembly 330.

During each cycle, the compressor 302 is configured to alternately pushthe air 114 into the adsorption bed 300 (through the first rotary valveassembly 306) and pull the nitrogen-rich gas 122 out of the adsorptionbed 300 (through the first rotary valve assembly 306). The compressor302 may be driven by a motor 350 and may include a sensor 352 (e.g., anencoder) configured to provide a signal 354 encoding the direction andspeed of rotation of the motor 350 to the control system 220. Referringto FIG. 7B, the motor 350 is configured to receive instructions from thecontrol system 220 encoded in a control signal 356. The instructions inthe control signal 356 instruct the motor 350 to switch on or off and/orindicate in which direction the motor 350 is to rotate when switched on.Further, the control signal 356 may instruct the motor 350 at whichspeed to run. Referring to FIG. 7A, when the motor 350 runs in a firstdirection, the compressor 302 pushes air into the adsorption bed 300. Onthe other hand, when the motor 350 runs in a second direction, thecompressor 302 pulls the nitrogen-rich gas 122 (see FIGS. 8C and 8D)from the adsorption bed 300. By way of a non-limiting example, the motor350 may be implemented as a brushless direct current motor.

FIG. 9 is an illustration of the metering valve 320. Referring to FIG.9, the pressure transducer PT3 is connected across the metering valve320. Thus, the pressure transducer PT3 may determine a pressuredifferential value across the metering valve 320. Referring to FIG. 7B,the pressure transducer PT3 provides a pressure differential signal 358encoding the pressure differential value to the control system 220.

Referring to FIGS. 7B and 9, the metering valve 320 may be driven by astepper motor 322 configured to receive a control signal 360 from thecontrol system 220 encoding a stepper position value. The stepper motor322 is configured to move to the stepper position value encoded in thecontrol signal 360. In the embodiment illustrated, the metering valve320 is a stepper driven proportioning valve characterized by threevariables: (1) valve position, (2) differential pressure across thevalve (as measured by the pressure transducer PT3), and (3) flow rate.When a particular flow rate is desired (e.g., entered by the user viathe flow rate input 248 depicted in FIG. 6), the control system 220 usesthe pressure differential signal 358 (encoding the pressure differentialvalue) and the particular flow rate to “look up” a corresponding stepperposition value in a characterization table 362. In other words, thecharacterization table 362 stores stepper position values eachassociated with a flow rate value and a pressure differential value.Thus, a particular pressure differential value and a particular flowrate value may be used by the control system 220 to determine a stepperposition value. Then, the control system 220 encodes the stepperposition value in the control signal 360 and sends it to the steppermotor 322. This process may be repeated occasionally (e.g., every fewmilliseconds) to provide an instantaneously desired oxygen flow rate.

Referring to FIG. 9, a position sensor 368 may be operatively coupled tothe metering valve 320 and used to determine a home position. Theposition sensor 368 provides a position signal 370 to the control system220 that encodes whether the metering valve 320 is in the home position(e.g., true or “on”) or at a position other than the home position(e.g., false or “off”).

Referring to FIG. 7A, the pressure regulator R2 may be characterized asbeing a back pressure regulator. The pressure regulator R2 may beconfigured to prevent the pressure inside the adsorption bed 300 fromexceeding a first threshold pressure value (e.g., approximately 10pounds per square inch (“PSIG”)). For example, the pressure regulator R2may be configured to allow oxygen to flow automatically from theadsorption bed 300 when the pressure inside the adsorption bed 300reaches the first threshold value. The pressure regulator R2 may also beconfigured to prevent gases from flowing into the adsorption bed 300.This allows the pressure regulator R2 to control the pressure during thefirst phase (see FIG. 8A) and the second phase (see FIG. 8B).

The pressure regulator R1 may be characterized as being a vacuumregulator. The pressure regulator R1 may be configured to prevent thepressure inside the adsorption bed 300 from falling below a secondthreshold pressure value (e.g., approximately −7 PSIG). Thus, thepressure regulator R1 regulates the pressure in the adsorption bed 300to the second threshold pressure during the third phase (see FIG. 8C)and the fourth phase (see FIG. 8D). For example, the pressure regulatorR1 may be configured to allow oxygen to flow automatically into theadsorption bed 300 (e.g., from the oxygen tank 312) when the pressureinside the adsorption bed 300 falls below the second threshold value.The pressure regulator R1 may also be configured to prevent gases insidethe adsorption bed 300 from flowing out of the adsorption bed 300 towardthe metering valve 320 (see FIG. 1).

The optional solenoid valves SV9 and SV10 may be configured to maintainthe pressure inside the oxygen tank 312 between a minimum thresholdpressure value (e.g., approximately 4 PSIG) and a maximum thresholdpressure value (e.g., approximately 10 PSIG). The solenoid valves SV9and SV10 are connected in a parallel arrangement to a conduit or flowline (not shown) that conducts the high-pressure oxygen 132 (e.g., fromthe high-pressure oxygen source 120 illustrated in FIG. 1) to the oxygentank 312. The control system 220 selectively activates and deactivatesthe solenoid valves SV9 and SV10 using control signals 380 and 382 (seeFIG. 7B), respectively, to maintain the pressure in oxygen tank 312between the minimum and maximum threshold pressure values. Thus,together the control system 220 and the solenoid valves SV9 and SV10perform the functions of a digital (on/off) regulator.

The control system 220 may automatically stop the oxygen assembly 210from performing the VPSA process when the high-pressure external oxygensource 120 is connected. For example, the control system 220 may slow orshut down the VPSA process when pressure in the oxygen tank 312 exceedsan upper threshold (e.g., 10 PSIG). In this manner, the control system220 may slow or shut down the VPSA process when the adsorption bed 300is operating or the high-pressure external oxygen source 120 isconnected. On the other hand, when the pressure inside the oxygen tank312 falls below a lower pressure threshold (e.g., 4 PSIG), the controlsystem 220 may restart or accelerate the VPSA process.

The oxygen tank 312 may be implemented as a rigid chamber configured tostore a predetermined amount of oxygen (e.g., about 56 cubic inches ofoxygen). The outlet silencer 311 helps muffle sounds created by thecompressor 302.

Referring to FIGS. 7A and 7B, the oxygen sensor 314 measures oxygenconcentration in the oxygen tank 312, and encodes an oxygenconcentration value in an oxygen concentration signal 378 provided tothe control system 220. The control system 220 may use the oxygenconcentration signal 378 to monitor the oxygen assembly 210 to ensure itis working properly. If the oxygen concentration signal 378 indicatesthe oxygen concentration is too low, the control system 220 may concludethat the oxygen assembly 210 is not functioning properly.

The pressure transducer PT2 monitors the pressure between the first andsecond rotary valve assemblies 306 and 330 (which may be characterizedas being a pump pressure supplied to the second rotary valve assembly330). Referring to FIG. 7B, the pressure transducer PT2 provides anelectrical pressure signal 374 encoding that pressure value to thecontrol system 220.

First Rotary Valve Assembly

FIG. 10A is a perspective view of a first side of an exemplaryembodiment of the first rotary valve assembly 306. FIG. 10B is aperspective view of a second side of the first rotary valve assembly 306opposite the first side. Referring to FIG. 10A, the first rotary valveassembly 306 includes a motor assembly 830 mounted to an outer housing832. The motor assembly 830 includes a stepper motor 833 (see FIG. 7B)and a shaft 836 (see FIGS. 10B and 10C). The stepper motor 833 isconfigured to rotate the shaft 836.

Referring to FIG. 10B, a position sensor 834 may be mounted on a printedcircuit board (“PCB”) 837 fastened to the outer housing 832 opposite themotor assembly 830. In such embodiments, the PCB 837 may include anopening through which an end of the shaft 836 opposite the motorassembly 830 may pass.

FIG. 10C depicts the first side of the first rotary valve assembly 306and the shaft 836 of the motor assembly 830. Other parts of the motorassembly 830 have been omitted in FIG. 10C. Referring to FIG. 10C, inthe embodiment illustrated, the outer housing 832 has an outer shapethat is generally cross or cruciform-shaped. Thus, the outer housing 832has four arms 841-844 that extend outwardly from a central region 845 ofthe outer housing 832. In the embodiment illustrated, the motor assembly830 (see FIG. 10A) is mounted to the central region 845.

FIG. 10D depicts the second side of the first rotary valve assembly 306with the outer housing 832 and the PCB 837 removed. As shown in FIG.10D, the arms 841-844 (see FIG. 10B) house poppet valves CV1-CV4,respectively. Inside the outer housing 832 (see FIG. 10B), the poppetvalves CV1 and CV3 are positioned opposite one another, and the poppetvalves CV2 and CV4 are positioned opposite one another. The first rotaryvalve assembly 306 includes a cam 850 mounted on the shaft 836 (seeFIGS. 10B and 10C) and configured to selectively actuate the poppetvalves CV1-CV4. The cam 850 rotates with the shaft 836 as the motorassembly 830 (see FIG. 10A) rotates the shaft 836. Referring to FIG. 7B,the position sensor 834 provides a position signal 835 to the controlsystem 220 that encodes whether the cam 850, the stepper motor 833 (seeFIGS. 10A and 10B), and/or the shaft 836 (see FIGS. 10B and 10C) is in ahome position (e.g., true or “on”) or at a position other than the homeposition (e.g., false or “off”).

Referring to FIG. 10C, each of the arms 841-844 is open at its distalend 846. The open distal ends 846 of the arms 841-844 are closed by endcaps 851-854, respectively. The end caps 851-854 may be fastened to theouter housing 832 by fasteners 855.

Referring to FIG. 10B, the arms 841-844 include inlet openings856A-856D, respectively, configured to receive a gas or mixture ofgases, and outlet openings 858A-858D, respectively, through which a gasor mixture of gases may exit.

Referring to FIG. 10D, each of the poppet valves CV1-CV4 includes anopen ended housing 860 with a lateral inlet 862 and a lateral outlet864. The lateral inlets 862 of the poppet valves CV1-CV4 are aligned andin fluid communication with the inlet openings 856A-856D, respectively,of the outer housing 832. Similarly, the lateral outlets 864 of thepoppet valves CV1-CV4 are aligned and in fluid communication with theoutlet openings 858A-858D, respectively, of the outer housing 832.

One or more seals 866 and 868 (e.g., O-ring type seals) may bepositioned between the outer housing 832 and the housing 860. Forexample, the seal 868 may be positioned between the lateral inlet 862and the lateral outlet 864. By way of another non-limiting example, oneof the seals 866 may be positioned between each of the open distal ends846 of the arms 841-844 and the end caps 851-854, respectively.

The poppet valves CV1-CV4 are substantially identical to one another.For the sake of brevity, only the poppet valve CV1 will be described indetail. FIG. 10E is an exploded perspective view of the poppet valveCV1, the end cap 851, and the fasteners 855. Referring to FIG. 10E, thehousing 860 has an open proximal end portion 870 opposite an open distalend portion 872. The open distal end portion 872 is closed by the endcap 851 when the end cap 851 is fastened to the outer housing 832.Similarly, the housings 860 of the poppet valves CV2-CV4 are closed attheir open distal end portions 872 by the end caps 852-853,respectively, when the end caps 852-854 are fastened to the outerhousing 832

FIG. 10F is a cross sectional view of the first rotary valve assembly306 with the cam 850 positioned to open the poppet valves CV2 and CV4.FIG. 10G is a cross sectional view of the first rotary valve assembly306 with the cam 850 positioned to open the poppet valves CV1 and CV3.

Referring to FIG. 10F, a generally cylindrically shaped guide portion876 extends inwardly from the open proximal end portion 870 (see FIG.10E) of the housing 860. An open-ended channel 877 is formed in theguide portion 876. A shoulder 878 is formed on the inside the housing860 between the lateral inlet and outlet 862 and 864.

Turning to FIG. 10E, inside the housing 860, the poppet valve CV1 has apushrod 880 biased away from the end cap 851 by a biasing assembly 884.Referring to FIG. 10F, the pushrod 880 extends through the channel 877and exits the housing 860 though the open proximal end portion 870 (seeFIG. 10E). Turning to FIG. 10E, the pushrod 880 may have acircumferential recess 879 form near its proximal end portion 881.

A ring-shaped diaphragm 886 may extend around the pushrod 880 near theproximal end portion 881. In the embodiment illustrated, the diaphragm886 has a circular central portion P2 having a center aperture 887through which the pushrod 880 extends with the inner edge portion of thecentral portion P2 positioned within the recess 879, and thereby thecentral portion P2 firmly grips the pushrod 880. The diaphragm 886 mayclose and seal the open proximal end portion 870 of the housing 860.However, the diaphragm 886 may flex or stretch longitudinally to allowthe pushrod 880 to move longitudinally with respect to the housing 860.In the embodiment illustrated in FIG. 10F, the diaphragm 886 has acircular outer peripheral portion P1 positioned between the openproximal end portion 870 of the housing 860 and the outer housing 832,and thereby the outer peripheral portion P1 is firmly clamped in place.

Referring to FIG. 10E, the circular outer peripheral portion P1 of thediaphragm 886 is connected to the circular central portion P2 by acurved or contoured intermediate portion P3. The intermediate portion P3may be characterized as being a convolute. A circle positioned midwaybetween the outer peripheral portion P1 and the central portion P2 maybe characterized as being located at the center of the convolute. Thediaphragm 886 has an effective area which extends from the circle at thecenter of the convolute to the central portion P2.

Turning to FIG. 10E, the pushrod 880 has a distal end portion 882opposite the proximal end portion 881. The proximal end portion 881 hasa cam follower 883 (see FIGS. 10C and 10E) formed therein. In theembodiment illustrated, the proximal end portion 881 may taper outwardlyand be generally cone-shaped. The cam follower 883 (see FIG. 10C) may beimplemented as a planar or contoured lower surface of the proximal endportion 881.

A ring-shaped seat 896 is fixedly attached to the shoulder 878 formed onthe inside the housing 860. In the embodiment illustrated, the seat 896has a central through-hole 897 through which the pushrod 880 extendsunobstructed.

The distal end portion 882 of the pushrod 880 has a longitudinallyextending channel 885 formed therein. The channel 885 is open at thedistal end portion 882 of the pushrod 880. A disc-shaped poppet member892 is fastened to the distal end portion 882 of the pushrod 880 by afastener 894 (e.g., a bolt, screw, and the like) that extends into theopen end of the channel 885. Thus, the fastener 894 couples the poppetmember 892 to the distal end portion 882 of the pushrod 880, which movestherewith as a unit when the pushrod 880 moves inside the housing 860.

Referring to FIG. 10F, when the poppet member 892 is pressed against theseat 896, the poppet member 892 closes the central through-hole 897 anddivides the interior of the housing 860 into a proximal chamber 900 anda distal chamber 902. Thus, the poppet member 892 may seal the proximaland distal chambers 900 and 902 from one another. The lateral inlet 862is in communication with the proximal chamber 900, and the lateraloutlet 864 is in communication with the proximal chamber 900. On theother hand, referring to FIG. 10G, when the poppet member 892 is spacedapart distally from the seat 896, the central through-hole 897 isuncovered and the proximal and distal chambers 900 and 902 are incommunication with one another. Thus, in this configuration, a gas ormixture of gases may flow between the proximal and distal chambers 900and 902. In other words, a pathway is opened between the lateral inletand outlet 862 and 864.

The distal end portion 882 of the pushrod 880 is adjacent the biasingassembly 884. In the embodiment illustrated, the biasing assembly 884includes a biasing member 888 (e.g., a coil spring), and an end cap 890.The biasing member 888 applies an inwardly directed force on the pushrod880, which helps insure the pushrod 880 maintains contact with the cam850. The end cap 890 rests upon the fastener 894 and is positionedbetween the disc-shaped poppet member 892 and the end cap 851. Thebiasing member 888 extends between the end cap 890 and the end cap 851and applies the biasing force to the end cap 890, which translates thatforce to the fastener 894 and/or the poppet member 892. In turn, thefastener 894 and/or the poppet member 892 translates the biasing forceto the pushrod 880.

The cam 850 may be characterized as having two lobes or high points 910and 912 opposite one another. When one of the high points 910 and 912 isadjacent the cam follower 883 (see FIGS. 10C and 10E) of the pushrod 880of the poppet valve CV1, the high point 910 or 912 pushes the pushrod880 outwardly toward the end cap 851. This pushes the disc-shaped poppetmember 892 away from the seat 896 (as illustrated in FIG. 10G) and opensthe central through-hole 897. This opens the poppet valve CV1 and allowsa gas or mixture of gases to flow though the poppet valve CV1. On theother hand, as illustrated in FIG. 10G, when neither of the high points910 and 912 are adjacent the cam follower 883 (see FIGS. 10C and 10E) ofthe pushrod 880 of the poppet valve CV1, the pushrod 880 is biasedinwardly away from the end cap 851 by the biasing assembly 884. Thepushrod 880 thereby pulls the disc-shaped poppet member 892 toward theseat 896 causing the poppet member 892 to cover or close the centralthrough-hole 897. This closes the poppet valve CV1 and prevents a gas ormixture of gases from flowing though the poppet valve CV1.

Because the ventilator 100 may be required to function over a long lifespan (e.g., more than about 30,000 hours), the first rotary valveassembly 306 may experience about 15,000,000 VPSA cycles. To satisfythis requirement, each of the poppet valves CV1-CV4 may have a“balanced” valve configuration. Whenever one of the poppet valvesCV1-CV4 is closed, pressure inside the proximal chamber 900 acts uponboth the effective area of the diaphragm 886 and a portion of the poppetmember 892 covering (or closing) the central through-hole 897 of theseat 896. The area of the portion of the poppet member 892 covering (orclosing) the central through-hole 897 of the seat 896 is approximatelyequal to the effective area of the diaphragm 886. When the pressureinside the proximal chamber 900 is negative (or a vacuum), an inwardly(toward the proximal chamber 900) directed force acts upon the effectivearea of the diaphragm 886. At the same time, an inwardly (toward theproximal chamber 900) directed force acts on the portion of the poppetmember 892 covering the central through-hole 897 of the seat 896.Similarly, when the pressure inside the proximal chamber 900 ispositive, an outwardly (away from the proximal chamber 900) directedforce acts upon the effective area of the diaphragm 886 and an outwardly(away from the proximal chamber 900) directed force acts on the portionof the poppet member 892 covering the central through-hole 897 of theseat 896. Thus, when the proximal chamber 900 is sealed by the poppetmember 892, forces directed in opposite directions act upon theeffective area of the diaphragm 886 and the area of the portion of thepoppet member 892 covering (or closing) the central through-hole 897 ofthe seat 896. Because (as mentioned above), the effective area of thediaphragm 886 and the area of the portion of the poppet member 892covering (or closing) the central through-hole 897 of the seat 896 areapproximately equal, net force on the pushrod 880 is zero. Thisbalancing feature helps reduce the force of the pushrod 880 on the camfollower 883 and the cam 850, thereby reducing the wear and extendingthe life.

As explained above, each of the poppet valves CV1-CV4 is biased into aclosed position by its biasing assembly 884. Each of the poppet valvesCV1-CV4 includes the cam follower 883 (see FIGS. 10C and 10E) that abutsthe cam 850. As the cam 850 rotates, it pushes opposing ones of thepoppet valves CV1-CV4 outwardly opening them. If the poppet valves CV1and CV3 are in open positions, the poppet valves CV2 and CV4 are inclosed positions and vice versa. Referring to FIG. 7B, the first rotaryvalve assembly 306 (e.g., the stepper motor 833) is configured toreceive a control signal 376 from the control system 220 encoding a camposition. The first rotary valve assembly 306 (e.g., the stepper motor833) is also configured to rotate the cam 850 to the position encoded inthe control signal 376.

Referring to FIG. 7A, the poppet valve CV3 (see FIG. 10G) is connectedto the compressor 302 and the adsorption bed 300. The control system 220makes the pressure inside the distal chamber 902 of the poppet valve CV3less than the pressure inside the proximal chamber 900 of the poppetvalve CV3 by configuring the compressor 302 to provide suction to thedistal chamber 902.

The poppet valve CV1 (FIG. 10G) is connected to the compressor 302 andthe outlet vent 124. The control system 220 makes the pressure insidethe distal chamber 902 of the poppet valve CV1 less than the pressureinside the proximal chamber 900 of the poppet valve CV1 by configuringthe compressor 302 to push the nitrogen-rich gas 122 (see FIGS. 8C and8D) into the proximal chamber 900.

When the poppet valves CV1 and CV3 are open as illustrated in FIG. 10G,the poppet valve CV3 receives the nitrogen-rich gas 122 (see FIGS. 8Cand 8D) from the adsorption bed 300 and provides it to the compressor302. At the same time, the poppet valve CV1 allows the nitrogen-rich gas122 pumped from the adsorption bed 300 (via the poppet valve CV3) by thecompressor 302 to flow out of the compressor 302 and exit the ventilator100 via the outlet vent 124. Optionally, the poppet valve CV3 may beconnected to the second rotary valve assembly 330. As will be explainedbelow, the compressor 302 may provide the suction 154 to the suctionassembly 152 via the second rotary valve assembly 330.

Referring to FIG. 7A, the poppet valve CV4 (see FIG. 10F) is connectedto the compressor 302 and the patient air intake 116. The control system220 makes the pressure inside the proximal chamber 900 of the poppetvalve CV4 less than the pressure inside the distal chamber 902 of thepoppet valve CV4 by configuring the compressor 302 to provide suction tothe proximal chamber 900.

The poppet valve CV2 (see FIG. 10F) is connected to the compressor 302and the adsorption bed 300. The control system 220 makes the pressureinside the distal chamber 902 of the poppet valve CV2 greater than thepressure inside the proximal chamber 900 of the poppet valve CV2 byconfiguring the compressor 302 to provide the pressurized air 114 pumpedby the compressor 302 to the distal chamber 902.

When the poppet valves CV2 and CV4 are open as illustrated in FIG. 10F,the poppet valve CV4 allows the air 114 to be pumped via the patient airintake 116 into the compressor 302. At the same time, the poppet valveCV2 provides the pressurized air 114 from the compressor 302 to theadsorption bed 300. Optionally, the poppet valve CV2 may be connected tothe second rotary valve assembly 330. As will be explained below, thegases 164 provided to the second rotary valve assembly 330 may be usedto implement the nebulizer assembly 162.

As mentioned above, in the embodiment illustrated, the oxygen assembly210 generates the oxygen 364 (see FIG. 8B) using the VPSA process, whichmay have four phases that are labeled “PHASE 1,” “PHASE 2,” “PHASE 3,”and “PHASE 4” across the top of FIG. 11.

In FIG. 11, an upper line 400 depicts pressure experienced by the bed ofnitrogen adsorbent material 344 (see FIGS. 8A-8D) during the four phasesof the VPSA process. Referring to FIG. 11, the line 400 may bedetermined by the control system 220 based on the electrical pressuresignal 374 (see FIG. 7B) provided by the pressure transducer PT2. Alower line 410 depicts feed flow rate through the bed of nitrogenadsorbent material 344 (see FIGS. 8A-8D) during the four-phases of theVPSA process.

Lines 421 and 423 show that the poppet valves CV1 and CV3, respectively,are transitioned from open (“passing”) to closed (“not passing”) at thebeginning of the first phase and then the poppet valves CV1 and CV3 aretransitioned from closed (“not passing”) to open (“passing”) at thebeginning of third phase. Thus, the poppet valves CV1 and CV3 are closedduring most of the first phase and all of the second phase. Further, thepoppet valves CV1 and CV3 are open during most of the third phase andall of the fourth phase.

Conversely, lines 422 and 424 show that the poppet valves CV2 and CV4,respectively, are transitioned from closed (“not passing”) to open(“passing”) at the beginning of the first phase and then the poppetvalves CV2 and CV4 are transitioned from open (“passing”) to closed(“not passing”) at the beginning of third phase. Thus, the poppet valvesCV2 and CV4 are open during most of the first phase and all of thesecond phase. Further, the poppet valves CV2 and CV4 are closed duringmost of the third phase and all of the fourth phase.

FIG. 12 is a flow diagram of a method 500 performed by the controlsystem 220. The method 500 at least partially implements the VPSAprocess. As the method 500 is performed, the pressure transducer PT2(see FIGS. 7A and 7B) occasionally obtains pressure values for theadsorption bed 300 and sends the electrical pressure signal 374 to thecontrol system 220.

In first block 502, the control system 220 begins the first phase of theVPSA process by opening the poppet valves CV2 and CV4, and closing thepoppet valves CV1 and CV3. At this point, the pressure regulator R2 isclosed.

In next block 504, the control system 220 instructs the motor 350 of thecompressor 302 to pump the air 114 from the patient air intake 116 intothe adsorption bed 300. The motor 350 of the compressor 302 may run at arelatively high speed while drawing the air 114 from the patient airintake 116.

In block 506, the control system 220 determines that the pressure insidethe adsorption bed 300 has reached the first threshold pressure value(e.g., approximately 10 PSIG). When the pressure inside the adsorptionbed 300 reaches the first threshold pressure value, the pressureregulator R2 automatically opens. At this point, the first phase endsand the second phase begins. During the second phase, nitrogen isadsorbed by the adsorption bed 300 from the air 114 and referring toFIG. 8B, the oxygen 346 (e.g., 90% pure oxygen) flows out of theadsorption bed 300 through the pressure regulator R2. The oxygen thatpasses through the pressure regulator R2 during the second phase isstored in the oxygen tank 312.

Returning to FIG. 12, in next block 508, at the start of the secondphase, the control system 220 reduces the speed of the motor 350.Referring to FIG. 8B, during the second phase, a mass transfer zone 430moves away from the first end 341 (in a direction identified by an arrow“D1”) through to the second end 343. Gas on a first side 432 of the masstransfer zone 430 near the first end 341 is air, and gas on a secondside 434 of the mass transfer zone 430 near the second end 343 is about90% oxygen. The compressor 302 may run relatively slowly during thesecond phase to facilitate effective nitrogen adsorbtion. In block 510,the control system 220 detects the end of the second phase, which endswhen the mass transfer zone 430 reaches the second end 343. The controlsystem 220 may determine the second phase has ended after apredetermined amount of time (e.g., about one second) has elapsed. Insome embodiments, the control system 220 may also use a secondary means(e.g., pressure) to help determine when the second phase has ended. Atthis point, the adsorption bed 300 is fully saturated with nitrogen, thesecond phase ends, and the third phase begins.

At the start of the third phase, in block 512, the control system 220opens the poppet valves CV1 and CV3, and closes the poppet valves CV2and CV4. At this point, the pressure regulator R1 is closed.

In next block 514, the control system 220 instructs the motor 350 of thecompressor 302 to pump the nitrogen-rich gas 122 from the adsorption bed300 and into the external environment through the outlet vent 124. Thecompressor 302 may run at a relatively high speed as it draws thenitrogen-rich gas 122 out of the adsorption bed 300.

In block 516, the control system 220 determines that the pressure insidethe adsorption bed 300 has reached the second threshold pressure value(e.g., approximately −7 PSIG). At this point, the third phase ends andthe fourth phase begins.

At the beginning of the fourth phase, in block 518, the control system220 may reduce the speed of the motor 350 to a relatively slow speed.

In block 520, the control system 220 purges the adsorption bed 300 withoxygen from the oxygen tank 312. In block 520, the pressure regulator R1opens automatically to allow the flow of “purge” oxygen 348 (see FIG.8D) from the oxygen tank 312 to flow through the adsorption bed 300(e.g., in a direction identified by an arrow “D2”). The mass transferzone 430 also moves away from the second end 343 (in a directionidentified by an arrow “D2”) through to the first end 341. The lowpressure inside the adsorption bed 300 combined with the flow of purgeoxygen 348 draws the nitrogen out and regenerates the adsorption bed300. When the purge is completed, the fourth phase ends, which completesone four-phase cycle, and the method 500 terminates. The control system220 may begin another cycle by returning to block 502 of the method 500.

FIGS. 13A-13D are schematic diagrams of the second rotary valve assembly330. The second rotary valve assembly 330 may be substantially similarto the first rotary valve assembly 306 (see FIGS. 10A and 10B). However,the second rotary valve assembly 330 includes a cam 530 with a singlelobe or high point 532, which is unlike the cam 850 of the first rotaryvalve assembly 306, which has two high points 910 and 912 (see FIG. 10F)opposite one another.

Referring to FIGS. 13A-13D, the cam 530 of the second rotary valveassembly 330 is configured to selectively actuate four poppet valvesCV5-CV8 one at a time. Each of the poppet valves CV5-CV8 may besubstantially similar to the poppet valve CV1 illustrated in FIG. 10E.

In the second rotary valve assembly 330, the poppet valves CV5 and CV7are positioned opposite one another. Similarly, the poppet valves CV6and CV8 are positioned opposite one another. The poppet valves CV5-CV8are biased into a closed position. Each of the poppet valves CV5-CV8 hasa pushrod 538 (substantially similar to the pushrod 880 depicted in FIG.10E) with a cam follower 540 (substantially similar to the cam follower883 depicted in FIG. 10C) that abuts the cam 530. As the cam 530rotates, it pushes only one of the pushrods 538 of the poppet valvesCV5-CV8 at a time outwardly and into an open position.

Further, as explained above with respect to the first rotary valveassembly 306, each of the poppet valves CV5-CV8 may include a poppetmember (substantially identical to the poppet member 892) configured tomove with respect to a seat (substantially identical to the seat 896) toselectively connect a proximal chamber (like the proximal chamber 900)with a distal chamber (like the distal chamber 902). In suchembodiments, after the cam 530 pushes the pushrod 538 of a selected oneof the poppet valves CV5-CV8 outwardly, the selected poppet valve opens.

Referring to FIG. 7B, the second rotary valve assembly 330 includes astepper motor 542 and a position sensor 544 substantially similar to thestepper motor 833 and the position sensor 834 of the first rotary valveassembly 306. The second rotary valve assembly 330 (e.g., the steppermotor 542) is configured to receive a control signal 546 from thecontrol system 220 encoding a cam position. The second rotary valveassembly 330 (e.g., the stepper motor 542) is also configured to rotatethe cam 530 to the position encoded in the control signal 546. Theposition sensor 544 provides a position signal 548 to the control system220 that encodes whether the stepper motor 542 and/or the cam 530 is ina home position (e.g., true or “on”) or at a position other than thehome position (e.g., false or “off”).

Referring to FIG. 13A, the poppet valve CV5 has an inlet 550 connectedto the suction connection 150 and an outlet 552 connected to the poppetvalve CV3 (see FIGS. 10D, 10F, and 10G). When the poppet valves CV1 andCV3 are open, the poppet valve CV5 may be opened (as shown in FIG. 13A)to receive the suction 154 from the compressor 302 and provide thesuction 154 to the suction connection 150. Any gases received from thesuction assembly 152 (see FIG. 1) via the suction connection 150, may bepumped by the compressor 302 out the outlet vent 124 via the poppetvalve CV1. The nitrogen-rich gas 122 may be pumped by the compressor 302at the same time the suction 154 is provided.

Referring to FIG. 13B, the poppet valve CV6 has an inlet 554 connectedto the nebulizer assembly 162 and an outlet 556 connected to the poppetvalve CV2. When the poppet valves CV2 and CV4 are open, the poppet valveCV6 may be opened (as shown in FIG. 13B) to provide the gases 164 to thenebulizer connection 160 instead of providing the air 114 to theadsorption bed 300. Thus, the compressor 302 may power the nebulizerassembly 162 (see FIG. 1).

Referring to FIG. 13C, the poppet valve CV7 has an inlet 558 connectedto the metering valve 320 and an outlet 560 connected to the accumulator202. When the poppet valve CV7 is open as shown in FIG. 13C, oxygenoutput from the metering valve 320 is provided to the accumulator 202.

Referring to FIG. 13D, the poppet valve CV8 has an inlet 562 connectedto the metering valve 320 and an outlet 564 connected to the patientcircuit 110. When the poppet valve CV8 is open as shown in FIG. 13D, theoxygen 364 (from the adsorption bed 300) and/or the oxygen from theoxygen tank 312 is provided directly to the patient circuit 110.

Control System

Referring to FIGS. 5B and 7B, the control system 220 includes a memory700 connected to one or more processors 710. The memory stores the table362 and instructions 720 executable by the processor(s) 710.

The processor(s) 710 may be implemented by one or more microprocessors,microcontrollers, application-specific integrated circuits (“ASIC”),digital signal processors (“DSP”), combinations or sub-combinationsthereof, or the like. The processor(s) 710 may be integrated into anelectrical circuit, such as a conventional circuit board, that suppliespower to the processor(s) 710. The processor(s) 710 may include internalmemory and/or the memory 700 may be coupled thereto. The presentinvention is not limited by the specific hardware component(s) used toimplement the processor(s) 710 and/or the memory 700.

The memory 700 is a computer readable medium that includes instructionsor computer executable components that are executed by the processor(s)710. The memory 700 may be implemented using transitory and/ornon-transitory memory components. The memory 700 may be coupled to theprocessor(s) 710 by an internal bus 715.

The memory 700 may include random access memory (“RAM”) and read-onlymemory (“ROM”). The memory 700 contains instructions and data thatcontrol the operation of the processor(s) 710. The memory 700 may alsoinclude a basic input/output system (“BIOS”), which contains the basicroutines that help transfer information between elements within theventilator 100.

Optionally, the memory 700 may include internal and/or external memorydevices such as hard disk drives, floppy disk drives, and opticalstorage devices (e.g., CD-ROM, R/W CD-ROM, DVD, and the like). Theventilator 100 may also include one or more I/O interfaces (not shown)such as a serial interface (e.g., RS-232, RS-432, and the like), anIEEE-488 interface, a universal serial bus (“USB”) interface, a parallelinterface, and the like, for the communication with removable memorydevices such as flash memory drives, external floppy disk drives, andthe like.

The processor(s) 710 is configured to execute software implementing theVPSA process (which may include performing the method 500 illustrated inFIG. 12) and/or delivering oxygen in accordance with oxygen deliverymethods described below. Such software may be implemented by theinstructions 720 stored in memory 700.

Oxygen Delivery

Referring to FIG. 1, as mentioned above, the ventilator 100 delivers theinspiratory gases 108 directly to the patient connection 106 (via thepatient circuit 110). Oxygen may be delivered to the patient 102 in oneof two ways: (1) as pulses of oxygen 140 delivered directly to thepatient connection 106, or (2) in the gases 112 that contain the air 114optionally blended with the oxygen 250 and/or the low pressure oxygen128 in the accumulator 202.

FIGS. 14A and 14B are graphs illustrating traditional delivery of oxygenby a conventional portable ventilator connected to an external lowpressure continuous flow source, such as a stand-alone oxygenconcentrator. In FIG. 14A, the conventional portable ventilator is usingtraditional volume controlled ventilation to deliver breaths. In bothFIGS. 14A and 14B, the x-axis is time. The inspiratory phase occursduring the duration T_(i). The exhalation phase occurs during a durationT_(E). The pause occurs during a duration T_(P).

In FIG. 14A, the y-axis is flow rate within the patient's airway.Referring to FIG. 14A, a dashed line 570 illustrates a continuous flowof oxygen delivered during both the inspiratory and expiratory phases. Asolid line 572 illustrates a flow of air provided by the conventionalportable ventilator during both the inspiratory and expiratory phases.The solid line 572 is determined by a set of desired ventilatorsettings.

An area 574 illustrates an inspiratory volume of air received by thepatient, and an area 575 illustrates an expiratory volume of airexpelled by the patient. The area 574 represents the desired total tidalvolume selected by the user.

A shaded area 576 illustrates a volume of effective oxygen provided tothe patient during the inspiratory phase. An area 578 illustrates avolume of oxygen that is delivered by the conventional portableventilator during the inspiratory phase but is unusable (e.g., trappedin one or more anatomical dead spaces). Together the areas 576 and 578form a volume of gases that exceed the desired ventilator settings(e.g., a desired total tidal volume). Specifically, together the areas574, 576, and 578 form a total inspiratory volume (of oxygen and air)delivered by the conventional portable ventilator that exceeds thedesired total tidal volume. An area 580 illustrates a volume of oxygendelivered by the conventional portable ventilator during the exhalationphase that is wasted by the conventional portable ventilator.

In FIG. 14B, the conventional portable ventilator is using traditionalpressure controlled ventilation to deliver breaths. Referring to FIG.14B, the y-axis is pressure within the patient's airway. A pressurevalue “PIP” identifies the peak inspiratory pressure input or desired bythe user. A solid line 581 illustrates patient airway pressure duringboth the inspiratory and expiratory phases. Unfortunately, as FIG. 14Billustrates, the continuous flow of oxygen (illustrated in FIG. 14A bythe dashed line 570) causes the pressure within the patient's airway toexceed the peak inspiratory pressure input by the user (the pressurevalue “PIP”).

As shown in FIGS. 14A and 14B, the conventional portable ventilator isinefficient. For example, the conventional portable ventilator wastesall of the continuous flow of oxygen (illustrated in FIG. 14A by thedashed line 570) delivered during non-inspiratory time. Further, becausethe continuous flow of oxygen delivered to the patient is not controlled(e.g., by ventilator volume or inspiratory pressure settings), only aportion of the oxygen (illustrated by the shaded area 576) delivered isactually effective. Further, the continuous flow of oxygen causes thepeak inspiratory pressure input by the user to be exceeded when pressurecontrolled ventilation is used. One reason for this problem is that theconventional ventilator does not know how much oxygen (e.g., volume orrate) is being delivered to the patient.

While FIGS. 14A and 14B depict the conventional portable ventilatorusing traditional volume controlled ventilation and traditional pressurecontrolled ventilation, respectively, to deliver breaths, a similarresult occurs when the conventional portable ventilator uses other typesof ventilation because the ventilator does not know how much oxygen(e.g., volume or rate) is being delivered to the patient. Thus, theventilator cannot accurately configure the breaths delivered (e.g., toachieve either a desired flow rate or pressure in the patient's airway).

FIGS. 15A and 15B are graphs illustrating oxygen delivery provided bythe ventilator 100 illustrated in FIGS. 1 and 4. In FIG. 15A, theventilator 100 is using volume controlled ventilation to deliverbreaths. In both FIGS. 15A and 15B, the x-axis is time. The inspiratoryphase occurs during the duration T_(i). The exhalation phase occursduring the duration T_(E). The pause occurs during the duration T_(P).

Referring to FIG. 15A, a solid line 582 illustrates a flow of airprovided by the ventilator 100 during both the inspiratory andexpiratory phases. The solid line 582 is determined by a set of desiredventilator settings (e.g., values entered via the user interface 200illustrated in FIG. 6). A shaded area 584 illustrates a volume ofeffective oxygen provided to the patient 102 at the beginning of theinspiratory phase. An area 586 illustrates a volume of air provided tothe patient 102 during the inspiratory phase. Together the areas 584 and586 form a total inspiratory volume (of oxygen and air) delivered by theventilator 100. As mentioned above, this volume is also referred to asthe total tidal volume. An area 588 illustrates an expiratory volume ofair expelled by the patient 102.

FIG. 15A illustrates delivering one of the pulses of oxygen 140 (seeFIG. 1) at the start of the inspiration phase before the gases 112 (seeFIG. 1) are provided. For example, the ventilator 100 may wait untilafter the pulse of oxygen has been delivered before delivering the gases112. Thus, at the start of each inspiration phase of each breath, thepatient 102 (see FIG. 1) may be receiving only the pulse (or bolus) ofoxygen from the ventilator 100. However, this is not a requirement. Inalternate embodiments, the flow of the gases 112 may begin before thedelivery of the bolus of oxygen has completed. In any event, the flow ofthe gases 112 are started before the end of the inspiration phase.

In FIG. 15B, the ventilator 100 is using pressure controlled ventilationto deliver breaths. Referring to FIG. 15B, the y-axis is pressure withinthe patient's airway. A solid line 589 illustrates patient airwaypressure during both the inspiratory and expiratory phases. As FIG. 15Billustrates, the pressure within the patient's airway does not exceedthe peak inspiratory pressure value input by the user (the pressurevalue “PIP”) using the pressure control input 237 (see FIG. 6).

As shown in FIGS. 15A and 15B, the ventilator 100 is more efficient thanthe conventional portable ventilator. For example, the ventilator 100does not provide a continuous flow of oxygen and therefore, avoidswasting oxygen during non-inspiratory times. Further, the totalinspiratory volume is in accordance with (and does not exceed) thedesired ventilator settings. And furthermore, the oxygen is delivered inthe first part of the breath where the oxygen provides betteroxygenation, as opposed to during the last part of the breath when theoxygen becomes trapped in the anatomical dead spaces. Further, becausethe ventilator 100 knows the total tidal volume delivered, theventilator 100 may configure the breaths not to exceed a user suppliedpeak inspiratory pressure value (e.g., when pressure ventilation isused). Thus, one of ordinary skill in the art through application of thepresent teachings could configure the ventilator 100 to deliver anydesired type of ventilation in which oxygen is delivered in the firstpart of the breath. Further, the delivery of the pulses of oxygen 140(see FIG. 1) may begin before the initiation of each breath.

Referring to FIG. 13D, for pulse dose delivery, the control system 220instructs the second rotary valve assembly 330 (via the control signal546 depicted in FIG. 7B) to rotate the cam 530 to open the poppet valveCV8. The inspiratory phase may be initiated by either the control system220 or the patient 102. After detecting the beginning of an inspiratoryphase, the control system 220 instructs the stepper motor 322 of themetering valve 320 to deliver a desired dose or pulse of oxygen to thepatient circuit 110, referred to as a “bolus.” Thus, the ventilator 100is configured to synchronize a bolus of oxygen with the patient'sbreathing. For example, the ventilator 100 may be configured to providethe volume (or bolus) of oxygen depicted by the area 584 of FIG. 15A.

The user interface 200 may be used to determine parameter values for thebolus. For example, if the oxygen flow equivalent input 244 (see FIG. 6)allows the user to select a numerical value (e.g., from 1 to 10), eachsuccessive number may represent an amount of “equivalent oxygenation”relative to a continuous flow of oxygen. For example, the number “2” mayprovide a bolus of oxygen at the beginning of a breath that wouldprovide oxygenation equivalent to a bleed-in flow of oxygen at twoliters per minute from an external source (e.g., the low pressure oxygensource 118 depicted in FIG. 1). By way of another non-limiting example,the user may select a numerical value within a predetermined range thatrepresents from about 0.2 liters per minute to about 9 liters per minutein increments of about 0.1 liters per minute.

Because at least some of the oxygen delivered using a hypotheticalcontinuous flow of oxygen is wasted, the control system 220 isconfigured to deliver an amount of oxygen in the bolus that is less thanan amount of oxygen that would be delivered by the continuous flow ofoxygen during the inspiration phase.

In alternate embodiments, the user may enter a pulse volume value usingthe oxygen pulse volume input 251 (see FIG. 6) that specifies the sizeof the bolus. The pulse volume value may be expressed in milliliters ora dimensionless value within a predetermined numerical range (e.g., from1 to 10). In such embodiments, each successive number may represent agreater amount of oxygen.

The control system 220 adjusts the delivery of the breath to account forthe bolus, and ensures that the breath is delivered in accordance withthe user setting of tidal volume (entered via the tidal volume input 242depicted in FIG. 6) or the peak inspiratory pressure value (e.g.,entered via the pressure control input 237 depicted in FIG. 6). By wayof a non-limiting example, the control system 220 may configure thebolus to have a volume that is less than about 75% of the total tidalvolume delivered. By way of another non-limiting example, the controlsystem 220 may configure the bolus to have a volume that is betweenabout 50% and about 75% of the total tidal volume delivered.

Further, the ventilator 100 is configured to adjust the parameter values(e.g., volume, pressure, etc.) of the inspiratory gases 108 to assurethe inspiratory gases 108 are delivered correctly. For example, if theuser (e.g., a clinician) uses the tidal volume input 242 (see FIG. 6) toset the total tidal volume value to 500 ml, and the oxygen pulse volumeinput 251 (see FIG. 6) to set the pulse volume value to 100 ml, thecontrol system 220 will set the air delivery from the accumulator 202 to400 ml, thus providing the correct total volume (500 ml=400 ml+100 ml)to the patient circuit 110.

The control system 220 may deliver a user-set bolus of oxygen (e.g., inthe gases 112 and/or the pulses of oxygen 140) to the patient connection106. The size of the bolus is controlled by the metering valve 320. Thecontrol system 220 reduces the flow of the gases 252 (see FIG. 5A) asmeasured by the internal flow transducer 212 (and encoded in the flowsignal 270 illustrated in FIG. 5B) to satisfy a user set tidal volumevalue (when volume ventilation is used) or a user set peak inspiratorypressure value (when pressure ventilation is used).

The total inspiratory flow rate and volume of the gases 112 (see FIG. 1)may be determined using the flow signal 270 (see FIG. 5B), and the pulsevolume may be determined using the signal 358 (see FIG. 7B) and thestepper position value (described above) of the metering valve 320.Further, the control system 220 controls the pulse (or bolus) volumeusing the control signal 360 (see FIG. 7B) sent to the stepper motor 322(see FIG. 7B) of the metering valve 320. The control system 220 sets theair delivery from the accumulator 202 using the control signal 278 (seeFIG. 5B) sent to the motor 272 of the blower 222.

Referring to FIG. 13C, for mixed oxygen delivery, the cam 530 of thesecond rotary valve assembly 330 is positioned so that the poppet valveCV7 is in the open position. The control system 220 determines theoxygen flow required at a given time to achieve a FI02 input by the user(e.g., via the FI02 input 246 depicted in FIG. 6). The FI02 may beexpressed within a range (e.g., about 21% to about 100%). The controlsystem 220 may use the control signal 360 (see FIG. 7B) to position themetering valve 320 to achieve the desired oxygen flow. The controlsystem 220 may use the oxygen concentration signal 276 (see FIG. 5B)from the oxygen sensor 227 to monitor the gases 252 that pass throughthe internal bacterial filter 230 and emerge as the gases 112.

Suction Assembly

Referring to FIG. 16, the suction assembly 152 may include a filter 800,a conventional suction canister 810, a conventional suction catheter812, and tubing 820 configured to be connected to the suction catheter812. The suction catheter 812 may be configured to be inserted insidethe patient connection 106.

Referring to FIG. 1, the suction assembly 152 provides a means to usethe suction 154 provided by the ventilator 100 to “vacuum” secretionsfrom the patient's airway. Referring to FIG. 10G, the control system 220positions the cam 850 of the first rotary valve assembly 306 to open thepoppet valves CV1 and CV3, and, referring to FIG. 13A, the controlsystem 220 positions the cam 530 of the second rotary valve assembly 330to open the poppet valve CV5. In this configuration, the compressor 302pulls gas and secretions from the suction catheter 812 (see FIG. 16),through the tubing 820 and into the suction canister 810 (see FIG. 16)where the liquid secretions are trapped. The filter 800 (e.g., ahydrophobic filter) may be used to further prevent patient secretionsfrom entering the ventilator 100 through the suction connection 150.However, gas pulled into the ventilator 100 continues through the firstand second rotary valve assemblies 306 and 330, and enters thecompressor 302. The control system 220 controls the speed of the motor350 of the compressor 302 to achieve the user set suction pressure, asmeasured by the pressure transducer PT2.

Nebulizer Assembly

Referring to FIG. 1, the nebulizer assembly 162 provides a means to usethe gases 164 provided by the ventilator 100 for delivering aerosolizedmedications to the patient's lung(s) 142. Referring to FIG. 10F, thecontrol system 220 positions the cam 850 of the first rotary valveassembly 306 to open the poppet valves CV2 and CV4, and, referring toFIG. 13B, the control system 220 positions the cam 530 of the secondrotary valve assembly 330 to open the poppet valve CV6. In thisconfiguration, gas flows from the compressor 302, through the first andsecond rotary valve assemblies 306 and 330, and on to the nebulizerassembly 162. The control system 220 controls the speed of the motor 350of the compressor 302 to maintain a desired pressure (e.g., about 12PSIG) as measured by the pressure transducer PT2. The first rotary valveassembly 306 may be cycled to synchronize medication delivery with theinspiratory phase as desired. In a manner similar to that used for pulsedose oxygen delivery, the control system 220 may compensate (or adjust)the breaths delivered to account for the additional volume delivered bythe nebulizer assembly 162.

The foregoing described embodiments depict different componentscontained within, or connected with, different other components. It isto be understood that such depicted architectures are merely exemplary,and that in fact many other architectures can be implemented whichachieve the same functionality. In a conceptual sense, any arrangementof components to achieve the same functionality is effectively“associated” such that the desired functionality is achieved. Hence, anytwo components herein combined to achieve a particular functionality canbe seen as “associated with” each other such that the desiredfunctionality is achieved, irrespective of architectures or intermedialcomponents. Likewise, any two components so associated can also beviewed as being “operably connected,” or “operably coupled,” to eachother to achieve the desired functionality.

While particular embodiments of the present invention have been shownand described, it will be obvious to those skilled in the art that,based upon the teachings herein, changes and modifications may be madewithout departing from this invention and its broader aspects and,therefore, the appended claims are to encompass within their scope allsuch changes and modifications as are within the true spirit and scopeof this invention. Furthermore, it is to be understood that theinvention is solely defined by the appended claims. It will beunderstood by those within the art that, in general, terms used herein,and especially in the appended claims (e.g., bodies of the appendedclaims) are generally intended as “open” terms (e.g., the term“including” should be interpreted as “including but not limited to,” theterm “having” should be interpreted as “having at least,” the term“includes” should be interpreted as “includes but is not limited to,”etc.). It will be further understood by those within the art that if aspecific number of an introduced claim recitation is intended, such anintent will be explicitly recited in the claim, and in the absence ofsuch recitation no such intent is present. For example, as an aid tounderstanding, the following appended claims may contain usage of theintroductory phrases “at least one” and “one or more” to introduce claimrecitations. However, the use of such phrases should not be construed toimply that the introduction of a claim recitation by the indefinitearticles “a” or “an” limits any particular claim containing suchintroduced claim recitation to inventions containing only one suchrecitation, even when the same claim includes the introductory phrases“one or more” or “at least one” and indefinite articles such as “a” or“an” (e.g., “a” and/or “an” should typically be interpreted to mean “atleast one” or “one or more”); the same holds true for the use ofdefinite articles used to introduce claim recitations. In addition, evenif a specific number of an introduced claim recitation is explicitlyrecited, those skilled in the art will recognize that such recitationshould typically be interpreted to mean at least the recited number(e.g., the bare recitation of “two recitations,” without othermodifiers, typically means at least two recitations, or two or morerecitations).

Accordingly, the invention is not limited except as by the appendedclaims.

The invention claimed is:
 1. A method of providing a breath to a humanpatient having a patient connection connected by a patient circuit to aventilator having a first ventilator connection and a different secondventilator connection, each of the first and second ventilatorconnections being in fluid communication with the patient circuit, themethod comprising: identifying, with the ventilator, initiation of aninspiratory phase of the breath; delivering a bolus of oxygen to thefirst ventilator connection before or during the inspiratory phase; anddelivering breathing gases comprising air to the second ventilatorconnection during the inspiratory phase, the ventilator isolating thebolus of oxygen delivered to the first ventilator connection from thebreathing gases delivered to the second ventilator connection.
 2. Themethod of claim 1, wherein the bolus of oxygen is delivered at theinitiation of the inspiratory phase of the breath.
 3. The method ofclaim 1, further comprising: identifying, with the ventilator, an end ofthe inspiratory phase of the breath; and terminating the delivery of thebolus of oxygen before the end of the inspiratory phase, wherein thebreathing gases are delivered after the delivery of the bolus of oxygenhas been terminated.
 4. The method of claim 1, further comprising:determining, with the ventilator, a volume of the bolus of oxygendelivered for the breath.
 5. The method of claim 1 for use with a userspecified total tidal volume, wherein the breathing gases delivered forthe breath have a first volume, the bolus of oxygen delivered for thebreath has a second volume, and combined the first and second volumesare substantially equal to the user specified total tidal volume.
 6. Themethod of claim 1 for use with a user specified peak inspiratorypressure value, wherein a combined pressure of the breathing gases andthe bolus of oxygen delivered for the breath does not exceed the userspecified peak inspiratory pressure value.
 7. A ventilator device foruse with a human patient having a patient connection couplable to apatient circuit, the ventilator device comprising: a ventilatorconnection couplable to the patient circuit; one or more first flowconduits in fluid communication with the ventilator connection; acompressor configured to deliver breathing gases to the one or morefirst flow conduits, which deliver the breathing gases to the ventilatorconnection; a patient oxygen outlet couplable to the patient circuit;one or more second flow conduits in fluid communication with the patientoxygen outlet; and an oxygen source configured to deliver oxygen to theone or more second flow conduits, which deliver the oxygen to thepatient oxygen outlet, wherein the patient oxygen outlet and the one ormore second flow conduits isolate the oxygen from the breathing gasesdelivered to the one or more first flow conduits and the ventilatorconnection.
 8. The ventilator device of claim 7, wherein the one or moresecond flow conduits includes a first conduit and a second conduit, andthe ventilator device further comprises: a valve, the first conduitbeing in fluid communication with the valve to deliver oxygen from theoxygen source to the valve, and the second conduit being in fluidcommunication with the valve to deliver oxygen from the valve to thepatient oxygen outlet, wherein opening the valve allows the oxygen toflow from the oxygen source to the patient oxygen outlet through thefirst and second conduits, and closing the valve prevents the oxygenfrom flowing from the oxygen source to the patient oxygen outlet throughthe first and second conduits.
 9. The ventilator device of claim 8,further comprising a control system configured to: (a) open the valve ator before a beginning of an inspiratory phase of a breath to therebyallow the oxygen to flow from the oxygen source to the patient oxygenoutlet; (b) close the valve before an end of the inspiratory phase ofthe breath to thereby prevent the oxygen from flowing from the oxygensource to the patient oxygen outlet; and (c) instruct the compressor todeliver the breathing gases before the end of the inspiratory phase ofthe breath.
 10. The ventilator device of claim 9, further comprising: aninput configured to receive a user specified total tidal volume, whereinthe breathing gases delivered for the breath have a first volume, theoxygen allowed to flow for the breath has a second volume, and combinedthe first and second volumes are substantially equal to the userspecified total tidal volume.
 11. The ventilator device of claim 9,further comprising: an input configured to receive a user specified peakinspiratory pressure value, wherein a combined pressure of the breathinggases delivered and the oxygen allowed to flow for the breath does notexceed the user specified peak inspiratory pressure value.
 12. Theventilator device of claim 9, wherein the control system is configuredto instruct the compressor to deliver the breathing gases after thevalve has been closed.
 13. The ventilator device of claim 9, furthercomprising: a user input configured to receive a user selected parametervalue, the control system being configured to leave the valve open untila volume of oxygen determined based at least in part on the userselected parameter value has flowed through the valve.
 14. Theventilator device of claim 9, wherein the oxygen source is configured tostore oxygen, and the ventilator device further comprises: an oxygengenerator in fluid communication with the oxygen source; and a sensorconfigured to provide a signal to the control system, the signalencoding at least one of a concentration of oxygen stored by the oxygensource and a pressure of the oxygen stored by the oxygen source, thecontrol system being configured to use the signal to determine whetheran amount of oxygen stored by the oxygen source is less than a thresholdvalue, and to operate the oxygen generator to deliver oxygen to theoxygen source when the control system determines the amount of oxygenstored by the oxygen source is less than the threshold value.
 15. Theventilator device of claim 9, for use with the patient circuit having asensor configured to detect a flow rate within the patient circuit andsend a signal encoding the flow rate, wherein the control system isconfigured to receive the signal from the sensor and use the signal todetect when the patient has initiated the beginning of the inspiratoryphase.
 16. The ventilator device of claim 9, further comprising: asensor configured to detect a flow rate within one of the one or morefirst flow conduits and send a signal to the control system encoding theflow rate, the control system being configured to use the signal todetect when the patient has initiated the beginning of the inspiratoryphase.
 17. The ventilator device of claim 9, further comprising: anaccumulator configured to deliver at least a portion of the breathinggases to the compressor via at least one of the one or more first flowconduits; and a sensor configured to detect a flow rate inside the atleast one of the one or more first flow conduits and send a signal tothe control system encoding the flow rate, the control system beingconfigured to use the signal to detect when the patient has initiatedthe beginning of the inspiratory phase.